Keaton is beautiful. Keaton is one of the most beautiful men who ever lived.
Both these guys started out as tumblers and discovered somewhere along the line that they were artists.
Keaton's camerawork is lovely. Chaplin could never be bothered with that sort of thing.
Chaplin lived in a larger world. His films are braver. Keaton never went beyond pushing the fat capitalist in the river (then fishing him out again.) There's nothing in the Keaton oeuvre as transgressive as The Great Dictator or M. Verdoux.
Keaton did a deal with the suits (perhaps he had to) and they screwed him; Chaplin never did and they tried to screw him and failed.
Keaton is a huge talent. Chaplin is a genius.
Sam Beckett made an insufferably pretentious film with Keaton. Its insufferably pretentious title is "Film". All the way through he insists on photographing Keaton from the back. One of the greatest faces in film history and you make a point of not showing it- words fail me!
Keaton eclipses Chaplin in their scene together in Limelight and Chaplin allows it to happen. I love it.