crossbar vs crosspiece

crossbar and crosspiece both are nouns.

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

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

crossbar (noun)	crosspiece (noun)
long thin horizontal crosspiece between two vertical posts	a transverse brace
game equipment consisting of a horizontal bar to be jumped or vaulted over	a horizontal beam that extends across something
a horizontal bar that goes across something