alto rilievo vs alto relievo

alto rilievo and alto relievo both are nouns.

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

As nouns, alto rilievo and alto relievo are synonyms defined as:

alto rilievo and alto relievo: a sculptural relief in which forms extend out from the background to at least half their depth

Other synonyms of alto rilievo include high relief.

alto rilievo (noun)	alto relievo (noun)
a sculptural relief in which forms extend out from the background to at least half their depth	a sculptural relief in which forms extend out from the background to at least half their depth