quarter round vs moulding

quarter round and moulding both are nouns.

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

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

quarter round: a convex molding having a cross section in the form of a quarter of a circle or of an ellipse
moulding: a decorative strip used for ornamentation or finishing

Other hypernyms of quarter round include molding.

quarter round (noun)	moulding (noun)
a convex molding having a cross section in the form of a quarter of a circle or of an ellipse	a preliminary sculpture in wax or clay from which a finished work can be copied
	a decorative recessed or relieved surface on an edge
	a decorative strip used for ornamentation or finishing
	sculpture produced by molding