echinus vs quarter round

echinus and quarter round both are nouns.

Word	Noun	Adjective	Verb	Adverb
echinus	Yes	No	No	No
quarter round	Yes	No	No	No

As nouns, quarter round is a hypernym of echinus; that is, quarter round is a word with a broader meaning than echinus:

echinus: ovolo molding between the shaft and the abacus of a Doric column
quarter round: a convex molding having a cross section in the form of a quarter of a circle or of an ellipse

Other hypernyms of echinus include ovolo, thumb.

echinus (noun)	quarter round (noun)
ovolo molding between the shaft and the abacus of a Doric column	a convex molding having a cross section in the form of a quarter of a circle or of an ellipse