half-relief vs rilievo

half-relief and rilievo both are nouns.

Word	Noun	Adjective	Verb	Adverb
half-relief	Yes	No	No	No
rilievo	Yes	No	No	No

As nouns, rilievo is a hypernym of half-relief; that is, rilievo is a word with a broader meaning than half-relief:

half-relief: a sculptural relief between low relief and high relief
rilievo: sculpture consisting of shapes carved on a surface so as to stand out from the surrounding background

Other hypernyms of half-relief include embossment, relief, relievo, sculptural relief.

half-relief (noun)	rilievo (noun)
a sculptural relief between low relief and high relief	sculpture consisting of shapes carved on a surface so as to stand out from the surrounding background