Russell knows how to win, not talking about this game but, he constantly proves that he can play good under pressure(which Luck cannot yet) and he has a more mature mind so he reads the field better and as a result, makes better decisions. The only thing Luck has over him is talent but, execution is more important in this sport.
He had had multiple comebacks including a great one in the playoffs so I'd say Luck is also good under pressure. Last night he wasn't great but it didn't matter with how they were overmatched. Besides, one game doesn't determine how he is as a player (same goes for RW yesterday)