heated vs heated up

heated and heated up both are adjectives.

Word	Noun	Adjective	Verb	Adverb
heated	No	Yes	No	No
heated up	No	Yes	No	No

As adjectives, heated and heated up are synonyms defined as:

heated and heated up: made warm or hot (`het' is a dialectal variant of `heated')

Other synonyms of heated include het, het up.

heated (adjective)	heated up (adjective)
made warm or hot (`het' is a dialectal variant of `heated')	made warm or hot (`het' is a dialectal variant of `heated')
marked by emotional heat; vehement