caption vs legend

caption and legend both are nouns.

Word	Noun	Adjective	Verb	Adverb
caption	Yes	No	Yes	No
legend	Yes	No	No	No

As nouns, caption and legend are synonyms defined as:

caption (noun)	legend (noun)
brief description accompanying an illustration	brief description accompanying an illustration
translation of foreign dialogue of a movie or TV program; usually displayed at the bottom of the screen	a story about mythical or supernatural beings or events
taking exception; especially a quibble based on a captious argument

caption (verb)	legend (verb)
provide with a caption, as of a photograph or a drawing