Difference Between Chtml::ajax And Chtml::ajaxbutton

The Class reference states the following

Chtml ajax() Generates the JavaScript that initiates an AJAX request.
CHtml ajaxButton() Generates a push button that can initiate AJAX requests.

Can someone explain what is meant exactly by than Generates the JavaScript that initiates an AJAX request and Generates a push button that can initiate AJAX requests.

I need to create a button that will do a ajax request to action in my controller and on success run a small javascript function.

Thank you