Comparing comedy of Chaplin and Keaton:
The foundation for the two characters is different. Chaplin’s character is mischievous or even roguish: he steals, is short-tempered, starts fights. Charlie instigates much of the action, and while he is graceful Charlie moves through a chaotic world. His flaunting of social convention leaves us wishing we could be so bold.
Keaton’s character is one of perseverance: he struggles to make due despite woe-begetting circumstances of bad luck. Buster responds to much of the action in a world where physical laws seem to temporarily suspend their norms – either for him (e.g. through his acrobatics) or against him (e.g. the ceiling pulling down). Both his acrobatics and interaction with the sets leaves us wishing we could have such control.
Their presentation is different. Charlie places his emotion in his eyes and then his hands; he creates intimacy through close-ups. Buster places his emotion in his shoulders and hips; he creates awe through his acrobatics.