APUSH , AP GOV

As someone who took AP Gov, yes there is a slight overlap. If you have taken APUSH it will definitely come in use for the first unit of AP Gov, where you learn about the Articles of Confederation and the Constitution, among other things.

Yes, APUSH focuses on American history while APGOV focuses on government systems. At the school I go to US History is taken freshman year and Gov is taken sophomore year. Usually both are a requirement.

Hope this helps!