masking piece vs masking

masking piece and masking both are nouns.

Word	Noun	Adjective	Verb	Adverb
masking piece	Yes	No	No	No
masking	Yes	No	No	No

As nouns, masking piece and masking are synonyms defined as:

masking piece and masking: scenery used to block the audience's view of parts of the stage that should not be seen

masking piece (noun)	masking (noun)
scenery used to block the audience's view of parts of the stage that should not be seen	the act of concealing the existence of something by obstructing the view of it
	scenery used to block the audience's view of parts of the stage that should not be seen
	the blocking of one sensation resulting from the presence of another sensation