_url VS. _path

from http://www.ruby-forum.com/topic/101346

The users_url helper generates a URL that includes the protocol and host 
name.  The users_path helper generates only the path portion.

users_url: http://localhost/users

users_path: /users

Mostly you should use the _path flavor. If you need to spec the host or 
protocol (like for talking to another app or service), then use the _url 
flavor.