cheddar vs rat cheese

cheddar and rat cheese both are nouns.

Word	Noun	Adjective	Verb	Adverb
cheddar	Yes	No	No	No
rat cheese	Yes	No	No	No

As nouns, rat cheese is a hyponym of cheddar; that is, rat cheese is a word with a more specific, narrower meaning than cheddar:

cheddar: hard smooth-textured cheese; originally made in Cheddar in southwestern England
rat cheese: informal names for American cheddar

Other hyponyms of cheddar include store cheese.

cheddar (noun)	rat cheese (noun)
hard smooth-textured cheese; originally made in Cheddar in southwestern England	informal names for American cheddar