What is the difference in a polyatomic ion that has its name end in (-ate) as compared to one with the same central element that ends in (-ite)

Answer 1

It's the number of O atoms in the polyatomic ion.
Na2SO4 is sodium sulfATE.
Na2SO3 is sodium sulfITE.
NaNO3 is sodium nitrATE.
NaNO2 is sodium nitrITE
Na3PO4 is sodium phosphATE.
Na3PO3 is sodium phosphITE
There is arsenate and arsenite
There is chlorate and chlorite
There is bromate ad bromite.