respond vs call back

respond and call back both are verbs.

Word	Noun	Adjective	Verb	Adverb
respond	No	No	Yes	No
call back	No	No	Yes	No

As verbs, call back is a hyponym of respond; that is, call back is a word with a more specific, narrower meaning than respond:

Other hyponyms of respond include counter, field, sass, come back, rejoin, repay, retort, return, riposte, bridle.

respond (verb)	call back (verb)
show a response or a reaction to something	recall knowledge from memory; have a recollection
respond favorably or as hoped	summon to return
react verbally	return or repeat a telephone call
	cause to be returned