Way different cases. Denzel has the same ticks in all of his movies, from Malcolm X to Remember the Titans to Training Day. Everytime he hears something he doesn't like, he turns his head quickly to the side while scoffing. Seriously, he does it as every character he's ever played. And he always gets really still when he gets mad, and stares at you. Leo plays similar characters while still making them so different from one another. He doesn't have the same ticks, and they just seem like completely different people. I feel like if you picked up Coach Boone and made him into a personal security guard that lost his family, he'd be Creasy Bear.
Denzel takes it to the extreme with the ticks, mannerisms, etc., but it seems that Leo has played the same two or three types of characters in all of his movies.
It also bothers me that he's never attempted to do a comedy. I understand that it's a completely different type of acting, but great actors like Hanks, DeNiro, Cranston, or even McConaughey have managed to do it.