portmanteau word vs neology

portmanteau word and neology both are nouns.

Word	Noun	Adjective	Verb	Adverb
portmanteau word	Yes	No	No	No
neology	Yes	No	No	No

As nouns, neology is a hypernym of portmanteau word; that is, neology is a word with a broader meaning than portmanteau word:

portmanteau word: a new word formed by joining two others and combining their meanings
neology: a newly invented word or phrase

Other hypernyms of portmanteau word include coinage, neologism.

portmanteau word (noun)	neology (noun)
a new word formed by joining two others and combining their meanings	the act of inventing a word or phrase
	a newly invented word or phrase