Difference between Nuxt default server and Nuxt Express server

diff-default-express-server.log

diff -x node_modules -x package-lock.json -x .nuxt --color -r default-server/nuxt.config.js express-server/nuxt.config.js
1c1
< import pkg from './package'
---
> const pkg = require('./package')
3c3,4
< export default {
---
>
> module.exports = {
diff -x node_modules -x package-lock.json -x .nuxt --color -r default-server/package.json express-server/package.json
2c2
<   "name": "default-server",
---
>   "name": "express-server",
8c8
<     "dev": "nuxt",
---
>     "dev": "cross-env NODE_ENV=development nodemon server/index.js --watch server",
10c10
<     "start": "nuxt start",
---
>     "start": "cross-env NODE_ENV=production node server/index.js",
15c15,16
<     "nuxt": "^2.4.0"
---
>     "nuxt": "^2.4.0",
>     "express": "^4.16.4"
diff -x node_modules -x package-lock.json -x .nuxt --color -r default-server/pages/index.vue express-server/pages/index.vue
6c6
<         default-server
---
>         express-server
Only in express-server: server

index.js

// express-server/server/index.js

const express = require('express')
const consola = require('consola')
const { Nuxt, Builder } = require('nuxt')
const app = express()

// Import and Set Nuxt.js options
let config = require('../nuxt.config.js')
config.dev = !(process.env.NODE_ENV === 'production')

async function start() {
  // Init Nuxt.js
  const nuxt = new Nuxt(config)

  const { host, port } = nuxt.options.server

  // Build only in dev mode
  if (config.dev) {
    const builder = new Builder(nuxt)
    await builder.build()
  } else {
    await nuxt.ready()
  }

  // Give nuxt middleware to express
  app.use(nuxt.render)

  // Listen the server
  app.listen(port, host)
  consola.ready({
    message: `Server listening on http://${host}:${port}`,
    badge: true
  })
}
start()