guppy vs rainbow fish

guppy and rainbow fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
guppy	Yes	No	No	No
rainbow fish	Yes	No	No	No

As nouns, guppy and rainbow fish are synonyms defined as:

guppy and rainbow fish: small freshwater fish of South America and the West Indies; often kept in aquariums

Other synonyms of guppy include Lebistes reticulatus.

guppy (noun)	rainbow fish (noun)
small freshwater fish of South America and the West Indies; often kept in aquariums	small freshwater fish of South America and the West Indies; often kept in aquariums