trotter vs race horse

trotter and race horse both are nouns.

Word	Noun	Adjective	Verb	Adverb
trotter	Yes	No	No	No
race horse	Yes	No	No	No

As nouns, race horse is a hypernym of trotter; that is, race horse is a word with a broader meaning than trotter:

trotter: a horse trained to trot; especially a horse trained for harness racing
race horse: a horse bred for racing

Other hypernyms of trotter include bangtail, racehorse.

trotter (noun)	race horse (noun)
a horse trained to trot; especially a horse trained for harness racing	a horse bred for racing
foot of a pig or sheep especially one used as food