They did much more than just rename. They changed the personalities and (sometimes) the spheres of influence. Athena (for example) was the center of greek power, while Minerva (the roman version) was not a military deity like the greek counterpart. They are two different goddesses, even though they were the same.
Ares to mars changed Ares from a bloodthirsty maniac to a respectable god of war.
Some gods didn't change at all from the Greek-Roman transition.
I'm taking a mythology class at the moment, so I had to clear this up.
Caption this Meme
