has_many in routes.rb

rubyonrails-talk
1

Hi    I saw map.namespace(:admin) do |admin|         admin.resources :accounts, :has_many => [ :credentials ] end

and I wrote like

map.namespace(:admin) do |admin|         admin.resources :accounts do |account|                 account.resources :credentials         end end

       The only difference I found is, in the first no helper methods are generated..I would like to know is that the only difference ?If not on which circumstances we use these two?

Thanks in advance Sijo