"The difference between Keaton and Chaplin is the difference
between poise and poetry, between the aristocrat and the tramp, between
adaptability and dislocation, between the function of things and the meaning of
things, between eccentricity and mysticism, between man as machine and man as
angel, between the Girl as a convention and the Girl as an ideal, between the
centripetal and the centrifugal tendencies of slapstick. Keaton is now
generally acknowledged as the superior director and inventor of visual forms.
There are those who would go further and claim Keaton as pure cinema as opposed
to Chaplin's theatrical cinema. Keaton's cerebral tradition of comedy was
continued by René Clair and Jacques Tati, but Keaton the actor, like Chaplin
the actor, has proved to be inimitable. Ultimately, Keaton and Chaplin
complement each other down the line to that memorably ghostly moment in
Limelight when they share the same tawdry dressing room as they prepare to face
their lost audience."
From The American Cinema: Directors and Directions 1929-1968, by Andrew Sarris