rooter vs railbird

rooter and railbird both are nouns.

Word	Noun	Adjective	Verb	Adverb
rooter	Yes	No	No	No
railbird	Yes	No	No	No

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

rooter: an enthusiastic devotee of sports
railbird: a fan of racing who watches races from the outer rail of the track

Other hyponyms of rooter include aficionado.

rooter (noun)	railbird (noun)
an enthusiastic devotee of sports	a fan of racing who watches races from the outer rail of the track