crossbar vs whiffletree

crossbar and whiffletree both are nouns.

Word	Noun	Adjective	Verb	Adverb
crossbar	Yes	No	No	No
whiffletree	Yes	No	No	No

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

crossbar: a horizontal bar that goes across something
whiffletree: a crossbar that is attached to the traces of a draft horse and to the vehicle or implement that the horse is pulling

Other hyponyms of crossbar include doubletree, swingletree, whippletree.

crossbar (noun)	whiffletree (noun)
long thin horizontal crosspiece between two vertical posts	a crossbar that is attached to the traces of a draft horse and to the vehicle or implement that the horse is pulling
game equipment consisting of a horizontal bar to be jumped or vaulted over
a horizontal bar that goes across something