What's the difference between "Save" and "Save and Submit" Button Actions in Nintex Forms?
I believe that the difference is that the Save button will only save the detail on the form, but not necessarily submit the form when used in a workflow task. However, in a list form the action basically is the same for both versions of the button.
Please look at the following useful post by Vadim Tabakman on the differences:
Retrieving data ...