topminnow vs molly

topminnow and molly both are nouns.

Word	Noun	Adjective	Verb	Adverb
topminnow	Yes	No	No	No
molly	Yes	No	No	No

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

topminnow: small usually brightly-colored viviparous surface-feeding fishes of fresh or brackish warm waters; often used in mosquito control
molly: popular aquarium fish

Other hyponyms of topminnow include Gambusia affinis, mosquitofish, platy, Platypoecilus maculatus, mollie.

topminnow (noun)	molly (noun)
small usually brightly-colored viviparous surface-feeding fishes of fresh or brackish warm waters; often used in mosquito control	popular aquarium fish
freshwater fish of Central America having a long swordlike tail; popular aquarium fish