rendering vs caption

rendering and caption both are nouns.

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

As nouns, caption is a hyponym of rendering; that is, caption is a word with a more specific, narrower meaning than rendering:

rendering: a written communication in a second language having the same meaning as the written communication in a first language
caption: translation of foreign dialogue of a movie or TV program; usually displayed at the bottom of the screen

Other hyponyms of rendering include mistranslation, crib, pony, trot, retroversion, subtitle, supertitle, surtitle.

rendering (noun)	caption (noun)
giving in acknowledgment of obligation	brief description accompanying an illustration
the act of interpreting something as expressed in an artistic performance	translation of foreign dialogue of a movie or TV program; usually displayed at the bottom of the screen
perspective drawing of an architect's design	taking exception; especially a quibble based on a captious argument
a coat of stucco applied to a masonry wall
an explanation of something that is not immediately obvious
a performance of a musical composition or a dramatic role etc.
a written communication in a second language having the same meaning as the written communication in a first language

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