crosspiece vs rung

crosspiece and rung both are nouns.

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

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

Other hyponyms of crosspiece include crossbar, rundle, spoke, round, stave, cross thwart, thwart, transom, traverse.

crosspiece (noun)	rung (noun)
a transverse brace	one of the crosspieces that form the steps of a ladder
a horizontal beam that extends across something	a crosspiece between the legs of a chair