brainiac vs intellectual

brainiac and intellectual both are nouns.

Word	Noun	Adjective	Verb	Adverb
brainiac	Yes	No	No	No
intellectual	Yes	Yes	No	No

As nouns, intellectual is a hypernym of brainiac; that is, intellectual is a word with a broader meaning than brainiac:

Other hypernyms of brainiac include intellect.

brainiac (noun)	intellectual (noun)
someone who has exceptional intellectual ability and originality	a person who uses the mind creatively

brainiac (adjective)	intellectual (adjective)
	appealing to or using the intellect
	involving intelligence rather than emotions or instinct
	of or associated with or requiring the use of the mind