Difference between include and extend for loading of a module.

extend_or_include.rb

module Mojule
  def dynamic_method
    if self.class.eql?(Class)
       puts "I am now a class method of #{self.name}"
    else
       puts "I am now an instance method of #{self.class}"
    end
  end
end

class Klass
  # extend Klass with Mojule
  extend  Mojule
end

class Classs
   #  include Mojule in Classs
   include Mojule
end

Klass.dynamic_method # => "I am now a class method of #{self.name}"
# Klass.new.dynamic_method
# => class_module_via_method.rb:26: undefined method `dynamic_method' for #<Klass:0xb76f4584> (NoMethodError)

Classs.new.dynamic_method # => "I am now an instance method of Classs"
# Classs.dynamic_method
# => class_module_via_method.rb:30: undefined method `dynamic_method' for Classs:Class (NoMethodError)