Comparison between gulp and Grunt. See http://markgoodyear.com/2014/01/getting-started-with-gulp/ for a write-up.

01-gulpfile.js

/*!
 * install task gulp
 * $ npm install -g browser-sync
 * $ npm install gulp-ruby-sass gulp-autoprefixer gulp-cssnano gulp-jshint gulp-concat gulp-uglify gulp-imagemin gulp-notify gulp-rename gulp-livereload gulp-cache del --save-dev
 */

// Load plugins
var gulp         = require('gulp'),
    sass         = require('gulp-ruby-sass'),
    autoprefixer = require('gulp-autoprefixer'),
    cssnano      = require('gulp-cssnano'),
    jshint       = require('gulp-jshint'),
    uglify       = require('gulp-uglify'),
    imagemin     = require('gulp-imagemin'),
    rename       = require('gulp-rename'),
    concat       = require('gulp-concat'),
    notify       = require('gulp-notify'),
    cache        = require('gulp-cache'),
    livereload   = require('gulp-livereload'),
    del          = require('del'),
    browserSync  = require('browser-sync').create(); // create a browser sync instance.

// Static server
gulp.task('browser-sync', function() {
  browserSync.init({
    server: {
      baseDir: "./"
    }
  });
});

/* Styles
--------------------------------------------------------------------------- */
gulp.task('styles', function() {
  return sass('assets/scss/main.scss', { style: 'expanded' })
    .pipe(autoprefixer('last 2 version'))
    .pipe(gulp.dest('assets/css'))
    .pipe(rename({ suffix: '.min' }))
    .pipe(cssnano())
    .pipe(gulp.dest('assets/css'))
    .pipe(browserSync.reload({stream: true}))
    .pipe(notify({ message: 'Styles task complete' }));
});


/* Scripts
--------------------------------------------------------------------------- */
gulp.task('scripts', function() {
  return gulp.src('assets/js/**/*.js')
    .pipe(jshint('.jshintrc'))
    .pipe(jshint.reporter('default'))
    .pipe(concat('main.js'))
    .pipe(gulp.dest('assets/js'))
    .pipe(rename({ suffix: '.min' }))
    .pipe(uglify())
    .pipe(gulp.dest('assets/js/min'))
    .pipe(notify({ message: 'Scripts task complete' }));
});


/* Images
--------------------------------------------------------------------------- */
gulp.task('images', function() {
  return gulp.src('assets/image/**/*')
    .pipe(cache(imagemin({ optimizationLevel: 3, progressive: true, interlaced: true })))
    .pipe(gulp.dest('assets/image'))
    .pipe(notify({ message: 'Images task complete' }));
});


/* Clean
--------------------------------------------------------------------------- */
gulp.task('clean', function() {
  return del(['assets/scss', 'assets/js', 'assets/image']);
});


/* Default task
--------------------------------------------------------------------------- */
gulp.task('default', ['clean'], function() {
  gulp.start('styles', 'scripts', 'images');
});


/* Watch
--------------------------------------------------------------------------- */
gulp.task('watch', ['browser-sync'], function () {

  // Watch .scss files
  gulp.watch('assets/scss/**/*.scss', ['styles']);

  // Watch .js files
  gulp.watch('assets/js/**/*.js', ['scripts']);

  // Watch image files
  gulp.watch('assets/image/**/*', ['images']);

  // browserSync
  gulp.watch("*.html").on('change', browserSync.reload);

  // Create LiveReload server
  livereload.listen();

  // Watch any files in dist/, reload on change
  gulp.watch(['assets/**']).on('change', livereload.changed);

});

02-Gruntfile.js

/*!
 * Grunt
 * $ npm install grunt-contrib-uglify grunt-autoprefixer grunt-contrib-cssmin grunt-contrib-imagemin grunt-contrib-sass grunt-contrib-watch grunt-contrib-concat grunt-contrib-clean grunt-contrib-jshint grunt-notify --save-dev
 */

module.exports = function(grunt) {

  grunt.initConfig({

    // Sass
    sass: {
      dist: {
        options: {
          style: 'expanded'
        },
        files: {
          'dist/styles/main.css': 'src/styles/main.scss'
        }
      }
    },

    // Autoprefix
    autoprefixer: {
      options: {
        browsers: [
          'last 2 version'
        ]
      },
      dist: {
        src: 'dist/styles/main.css'
      }
    },

    // CSS minify
    cssmin: {
      dist: {
        files: {
          'dist/styles/main.min.css': 'dist/styles/main.css'
        }
      }
    },

    // JShint
    jshint: {
      files: ['src/scripts/**/*.js'],
      options: {
        jshintrc: '.jshintrc'
      }
    },

    // Concat
    concat: {
      js: {
        src: ['src/scripts/**/*.js'],
        dest: 'dist/scripts/main.js'
      },
    },

    // Uglify
    uglify: {
      dist: {
        src: 'dist/scripts/main.js',
        dest: 'dist/scripts/main.min.js'
      },
    },

    // Imagemin
    imagemin: {
      dist: {
        options: {
          optimizationLevel: 3,
          progressive: true,
          interlaced: true
        },
        files: [{
          expand: true,
          cwd: 'src/images',
          src: ['**/*.{png,jpg,gif}'],
          dest: 'dist/images'
        }]
      }
    },

    // Clean
    clean: {
      build: ['dist/styles', 'dist/scripts', 'dist/images']
    },

    // Notify
    notify: {
      styles: {
        options: {
          message: 'Styles task complete',
        }
      },
      scripts: {
        options: {
          message: 'Scripts task complete',
        }
      },
      images: {
        options: {
          message: 'Images task complete',
        }
      },
    },

    // Watch
    watch: {
      styles: {
        files: 'src/styles/**/*.scss',
        tasks: ['sass', 'autoprefixer', 'cssmin', 'notify:styles'],
      },
      scripts: {
        files: 'src/scripts/**/*.js',
        tasks: ['concat', 'uglify', 'notify:scripts'],
      },
      images: {
        files: 'src/images/**/*',
        tasks: ['imagemin', 'notify:images'],
      },
      livereload: {
        options: { livereload: true },
        files: [
          'dist/styles/**/*.css',
          'dist/scripts/**/*.js',
          'dist/images/**/*'
        ]
      }
    }
  });

  // Default task
  grunt.registerTask('default', [
    'jshint',
    'clean',
    'concat',
    'uglify',
    'sass',
    'autoprefixer',
    'cssmin',
    'imagemin'
  ]);

  // Load plugins
  grunt.loadNpmTasks('grunt-contrib-uglify');
  grunt.loadNpmTasks('grunt-autoprefixer');
  grunt.loadNpmTasks('grunt-contrib-cssmin');
  grunt.loadNpmTasks('grunt-contrib-sass');
  grunt.loadNpmTasks('grunt-contrib-watch');
  grunt.loadNpmTasks('grunt-contrib-concat');
  grunt.loadNpmTasks('grunt-contrib-jshint');
  grunt.loadNpmTasks('grunt-contrib-imagemin');
  grunt.loadNpmTasks('grunt-contrib-clean');
  grunt.loadNpmTasks('grunt-notify');

};

Gulp-v2.js

/*!
 * install task gulp
 * $ npm install -g browser-sync
 * $ npm install gulp-ruby-sass gulp-autoprefixer gulp-cssnano gulp-jshint gulp-concat gulp-uglify gulp-imagemin gulp-notify gulp-rename gulp-livereload gulp-cache del --save-dev
 */

// Load plugins
var gulp         = require('gulp'),
    sass         = require('gulp-ruby-sass'),
    autoprefixer = require('gulp-autoprefixer'),
    cssnano      = require('gulp-cssnano'),
    jshint       = require('gulp-jshint'),
    uglify       = require('gulp-uglify'),
    imagemin     = require('gulp-imagemin'),
    rename       = require('gulp-rename'),
    concat       = require('gulp-concat'),
    notify       = require('gulp-notify'),
    cache        = require('gulp-cache'),
    livereload   = require('gulp-livereload'),
    del          = require('del'),
    sourcemaps   = require('gulp-sourcemaps');

/* Styles
--------------------------------------------------------------------------- */
gulp.task('styles', function() {
  return sass('assets/sass/style.scss', { sourcemap: true, style: 'expanded' })
    .pipe(sourcemaps.init())
    .pipe(autoprefixer('last 2 version'))
    .pipe(gulp.dest('./'))
    .pipe(cssnano())
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest('./'))
    .pipe(notify({ message: 'Styles task complete' }));
});


/* Scripts
--------------------------------------------------------------------------- */
var js = [
  './assets/js/vendor/jquery-1.11.2.min.js',
  './assets/js/vendor/jquery.maskedinput.min.js',
  './assets/js/vendor/scrollreveal.min.js'
];

gulp.task('scripts', function() {
  return gulp.src('./assets/js/main.js')
    .pipe(concat('all.js'))
    .pipe(gulp.dest('assets/js/min'))
    .pipe(rename({ suffix: '.min' }))
    .pipe(uglify())
    .pipe(gulp.dest('assets/js/min'))
    .pipe(notify({ message: 'Scripts task complete' }));
});


/* Images
--------------------------------------------------------------------------- */
gulp.task('images', function() {
  return gulp.src('assets/images/**/*')
    .pipe(cache(imagemin({ optimizationLevel: 3, progressive: true, interlaced: true })))
    .pipe(gulp.dest('assets/images'))
    .pipe(notify({ message: 'Images task complete' }));
});


/* Clean
--------------------------------------------------------------------------- */
gulp.task('clean', function() {
  return del(['assets/sass', 'assets/js', 'assets/images']);
});


/* Default task
--------------------------------------------------------------------------- */
gulp.task('default', ['clean'], function() {
  gulp.start('styles', 'scripts', 'images');
});


/* Watch
--------------------------------------------------------------------------- */
gulp.task('watch', function () {

  // Watch .scss files
  gulp.watch('assets/sass/**/*.scss', ['styles']);

  // Watch .js files
  gulp.watch('assets/js/**/*.js', ['scripts']);

  // Watch image files
  // gulp.watch('assets/images/**/*', ['images']);

  // Create LiveReload server
  livereload.listen();

  // Watch any files in dist/, reload on change
  gulp.watch(['assets/css/**']).on('change', livereload.changed);
  gulp.watch(['assets/js/min/**']).on('change', livereload.changed);
  // gulp.watch(['assets/images/**']).on('change', livereload.changed);

});

package.json

{
  "name": "name",
  "title": "Name",
  "version": "1.0.0",
  "homepage": "http://www.name.com.br/",
  "description": "name",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Elias Faiçal - http://eliasfaical.com.br",
  "license": {
    "type": "MIT"
  },
  "devDependencies": {
    "del": "^2.2.2",
    "gulp": "^3.9.1",
    "gulp-autoprefixer": "^3.1.1",
    "gulp-cache": "^0.4.5",
    "gulp-concat": "^2.6.1",
    "gulp-cssnano": "^2.1.2",
    "gulp-imagemin": "^3.1.1",
    "gulp-jshint": "^2.0.4",
    "gulp-livereload": "^3.8.1",
    "gulp-notify": "^3.0.0",
    "gulp-rename": "^1.2.2",
    "gulp-ruby-sass": "^2.1.1",
    "gulp-sourcemaps": "^2.4.1",
    "gulp-uglify": "^2.0.1",
    "jshint": "^2.9.4"
  }
}