wheeler vs wheel horse

wheeler and wheel horse both are nouns.

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

As nouns, wheeler and wheel horse are synonyms defined as:

wheeler and wheel horse: a draft horse harnessed behind others and nearest the wheels of a vehicle

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