basso relievo vs rilievo

basso relievo and rilievo both are nouns.

Word	Noun	Adjective	Verb	Adverb
basso relievo	Yes	No	No	No
rilievo	Yes	No	No	No

As nouns, rilievo is a hypernym of basso relievo; that is, rilievo is a word with a broader meaning than basso relievo:

basso relievo: a sculptural relief in which forms extend only slightly from the background; no figures are undercut
rilievo: sculpture consisting of shapes carved on a surface so as to stand out from the surrounding background

Other hypernyms of basso relievo include embossment, relief, relievo, sculptural relief.

basso relievo (noun)	rilievo (noun)
a sculptural relief in which forms extend only slightly from the background; no figures are undercut	sculpture consisting of shapes carved on a surface so as to stand out from the surrounding background