heft up vs heft

heft up is not a noun while heft is a noun.

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

As verbs, heft up and heft are synonyms defined as:

Other synonyms of heft up include heave, heave up.

heft up (noun)	heft (noun)
	the property of being large in mass

heft up (verb)	heft (verb)
lift or elevate	lift or elevate
	test the weight of something by lifting it