The main difference is that Harlequin is a fictional character from Commedia dell'arte known for his physical comedy and checkered costume, while a jester was a real court entertainer with a broader role, including humor, music, and social commentary.

While jesters utilized verbal wit, satire, and sometimes physical comedy to amuse their audiences, harlequins were more physically oriented performers. Harlequins often engaged in mime or slapstick routines, telling stories through exaggerated actions rather than words.

When used as nouns, harlequin means a pantomime fool, typically dressed in checkered colorful clothes, whereas jester means one who jests, jokes or mocks. Harlequin is also verb with the meaning: to remove or conjure away, as if by a harlequin's trick.