Inside combat, Creed will avoid killing until they force him to. He has fought with defined rules of engagement for the last seventy years. That sense of guilt at operating outside even the least restrictive framework will fuel a smoldering rage.

Victor doesn't mind killing his enemies, but likes to act within his moral framework. 

Outside the games if he doesn't have contact with other prisoners, he will use the time to train, meditate and test the limits of his world.

Creed, once it is clear he must kill will do so with speed and efficiency. If they escape he'll act as best he can to get as many victims free and faraway as possible.

It will be very interesting to see how he reacts going from a respected member of society back to being a second class citizen.

And perhaps the triggering event that was avoided for this Victor will be faced wherever he winds up