I'm assuming you also meant the god's characterization as well, which is quite different between the two mythos.
Some of the major differences, however, include:
Greek mythology was centered around the myths(specifically heroes) and the natural world, whereas Roman was more centered around Rome.
The greeks imagined their gods as beautiful people, at the physical peak, while the roman gods didn't have much of a physical appearance, only what the people imagined them to be.
Afterlife is seen as something different as well. The greeks placed a much higher value on your physical life, while the romans placed a high importance on making sure you secure a good place in the afterlife when you die.
Is this enough or do you need more?
