wheeler vs draft horse

wheeler and draft horse both are nouns.

Word	Noun	Adjective	Verb	Adverb
wheeler	Yes	No	No	No
draft horse	Yes	No	No	No

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

wheeler: a draft horse harnessed behind others and nearest the wheels of a vehicle
draft horse: horse adapted for drawing heavy loads

Other hypernyms of wheeler include draught horse, dray horse.

wheeler (noun)	draft horse (noun)
a draft horse harnessed behind others and nearest the wheels of a vehicle	horse adapted for drawing heavy loads
someone who makes and repairs wooden wheels
a person who rides a bicycle
the man at the outermost end of the rank in wheeling