bas relief vs sculptural relief

bas relief and sculptural relief both are nouns.

Word	Noun	Adjective	Verb	Adverb
bas relief	Yes	No	No	No
sculptural relief	Yes	No	No	No

As nouns, sculptural relief is a hypernym of bas relief; that is, sculptural relief is a word with a broader meaning than bas relief:

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

Other hypernyms of bas relief include embossment, relief, relievo, rilievo.

bas relief (noun)	sculptural relief (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