fancier vs bird fancier

fancier and bird fancier both are nouns.

Word	Noun	Adjective	Verb	Adverb
fancier	Yes	No	No	No
bird fancier	Yes	No	No	No

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

Other hyponyms of fancier include animal fancier, maniac, technophile.

fancier (noun)	bird fancier (noun)
a person having a strong liking for something	a person with a strong interest in birds