visual joke vs sight gag

visual joke and sight gag both are nouns.

Word	Noun	Adjective	Verb	Adverb
visual joke	Yes	No	No	No
sight gag	Yes	No	No	No

As nouns, visual joke and sight gag are synonyms defined as:

visual joke and sight gag: a joke whose effect is achieved by visual means rather than by speech (as in a movie)

visual joke (noun)	sight gag (noun)
a joke whose effect is achieved by visual means rather than by speech (as in a movie)	a joke whose effect is achieved by visual means rather than by speech (as in a movie)