basso rilievo vs relievo

basso rilievo and relievo both are nouns.

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

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

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

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

basso rilievo (noun)	relievo (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