greyhound vs whippet

greyhound and whippet both are nouns.

Word	Noun	Adjective	Verb	Adverb
greyhound	Yes	No	No	No
whippet	Yes	No	No	No

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

greyhound: a tall slender dog of an ancient breed noted for swiftness and keen sight; used as a racing dog
whippet: small slender dog of greyhound type developed in England

Other hyponyms of greyhound include Italian greyhound.

greyhound (noun)	whippet (noun)
a tall slender dog of an ancient breed noted for swiftness and keen sight; used as a racing dog	small slender dog of greyhound type developed in England