doubletree vs crossbar

doubletree and crossbar both are nouns.

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

As nouns, crossbar is a hypernym of doubletree; that is, crossbar is a word with a broader meaning than doubletree:

doubletree: a crossbar on a wagon or carriage to which two whiffletrees are attached in order to harness two horses abreast
crossbar: a horizontal bar that goes across something

doubletree (noun)	crossbar (noun)
a crossbar on a wagon or carriage to which two whiffletrees are attached in order to harness two horses abreast	long thin horizontal crosspiece between two vertical posts
	game equipment consisting of a horizontal bar to be jumped or vaulted over
	a horizontal bar that goes across something