heat up vs crispen

heat up and crispen both are verbs.

Word	Noun	Adjective	Verb	Adverb
heat up	No	No	Yes	No
crispen	No	No	Yes	No

As verbs, crispen is a hyponym of heat up; that is, crispen is a word with a more specific, narrower meaning than heat up:

Other hyponyms of heat up include crisp, toast, scald, soak, calcine, preheat, overheat, scorch, sear, bake, broil, reheat.

heat up (verb)	crispen (verb)
make hot or hotter	make brown and crisp by heating
gain heat or get hot
make more intense