Two differents guys, but very similarity (Both are very-over-of-the-top)
Jack Nicholson was a great Joker in his moment, but today, We can see that he's Cesar Romero in Burton vision.
The Mask... Well, I don't know how the heck a violent character was played by Jim Carrey (Weird)
Joker (C) Warner Bros/DC Comics
The Mask (C): Dark Horse/New Line Cinema