polyglot vs bilingual

polyglot and bilingual both are nouns.

Word	Noun	Adjective	Verb	Adverb
polyglot	Yes	Yes	No	No
bilingual	Yes	Yes	No	No

As nouns, bilingual is a hyponym of polyglot; that is, bilingual is a word with a more specific, narrower meaning than polyglot:

Other hyponyms of polyglot include bilingualist, transcriber, translator.

polyglot (noun)	bilingual (noun)
a person who speaks more than one language	a person who speaks two languages fluently

polyglot (adjective)	bilingual (adjective)
having a command of or composed in many languages	using or knowing two languages