elephantine vs giant

elephantine is not a noun while giant is a noun.

Word	Noun	Adjective	Verb	Adverb
elephantine	No	Yes	No	No
giant	Yes	Yes	No	No

As adjectives, elephantine and giant are synonyms defined as:

Other synonyms of elephantine include gargantuan, jumbo.

elephantine (noun)	giant (noun)
	any creature of exceptional size
	an unusually large enterprise
	a very bright star of large diameter and low density (relative to the Sun)
	someone that is abnormally large and powerful
	a person of exceptional importance and reputation
	an imaginary figure of superhuman size and strength; appears in folklore and fairy tales
	a very large person; impressive in size or qualities

elephantine (adjective)	giant (adjective)
of great mass; huge and bulky	of great mass; huge and bulky