Nah, not exactly. The Romans gave a decidedly "own" twist to their mythologies and religion. Many of their deities are parallels of the Greek ones, but, well, different. Mars, as a god of war, was decidedly less barbaric and more cunning than his Greek counterpart Ares. It also mattered what archetype they invoked; Mars Ultor was specifically "Mars the avenger", whom was invoked when on a campaign of revenge against for example the Parthians who had stolen several Eagle standards.

Others are uniquely Roman and don't even have a direct Greek counterpart. Janus, the two-faced god of doors and new beginnings, was such a god. He was supremely important in all Roman religious cults and was invoked first, even before Jupiter, since he was held to be the "door to all deities".