low-necked vs low-cut

low-necked and low-cut both are adjectives.

Word	Noun	Adjective	Verb	Adverb
low-necked	No	Yes	No	No
low-cut	No	Yes	No	No

As adjectives, low-necked and low-cut are synonyms defined as:

Other synonyms of low-necked include decollete.

low-necked (adjective)	low-cut (adjective)
(of a garment) having a low-cut neckline	having a low-cut back
	(of a garment) having a low-cut neckline