the second is a path relative to the root of your application.
Example is the name of my project and also the context root. I am using websphere server which uses 9080 as the default port. I have mentioned the form tag with action in my html file.
I access my html form as:
http://localhost:9080/Example/index.html
When I mention / in the front in the action attribute like this (/a), on submission of the html form the url becomes
http://localhost:9080/a
How are you saying it is a path relative to the root of the application? The root in the case of this application is Example, but that disappears on the submission of the form.