I'm probably in the minority but when I see "save", I assume it's "saving my progress". In a user creation form, even just "create" is clearer than "save".
But then we're back in "is it telling me to create the user again when I already clicked the other button on creating a user on the other page?" territory. I think we should use whatever feels right and A/B test the hell out of it, but spend more time actually solving more substantial problems that the copy on a submit button.
