heat up vs soak

heat up is not a noun while soak is a noun.

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

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

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

heat up (noun)	soak (noun)
	washing something by allowing it to soak
	the process of becoming softened and saturated as a consequence of being immersed in water (or other liquid)

heat up (verb)	soak (verb)
make hot or hotter	fill, soak, or imbue totally
gain heat or get hot	cover with liquid; pour liquid onto
make more intense	heat a metal prior to working it
	become drunk or drink excessively
	make drunk (with alcoholic drinks)
	beat severely
	submerge in a liquid
	rip off; ask an unreasonable price
	leave as a guarantee in return for money