And your point is? The Ares in the Marvel Cinematic Universe that is on Sakaar, from what we know, is the Olympian God, however, it is not confirmed that he has the title of "God of War". There are not two Ares in the MCU, just as there are not two Thors.
Yes, this is the Ares from Greek mythology. There is only one Ares in the MCU, and that is the mythological one. We just don't have confirmation that he has been given the title of "God of War", despite it being a strong possibility.
In hopes of clarifying any confusion, in the MCU, Ares' species is a God and he is an Olympian who is worshipped in Greek mythology. Now, Gods have titles, such as Thor being the "God of Thunder" (albeit more lightning). Ares, in the mythology, is the God of War, but it is not known if the real Ares has the title of "God of War". The mythology is simply humans' own interpretations of the Gods, but not the Gods themselves.