ovolo vs echinus

ovolo and echinus both are nouns.

Word	Noun	Adjective	Verb	Adverb
ovolo	Yes	No	No	No
echinus	Yes	No	No	No

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

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

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