call back vs respond

call back and respond both are verbs.

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

As verbs, respond is a hypernym of call back; that is, respond is a word with a broader meaning than call back:

Other hypernyms of call back include answer, reply.

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