backscratcher vs scratcher

backscratcher and scratcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
backscratcher	Yes	No	No	No
scratcher	Yes	No	No	No

As nouns, scratcher is a hypernym of backscratcher; that is, scratcher is a word with a broader meaning than backscratcher:

backscratcher (noun)	scratcher (noun)
a long-handled scratcher for scratching your back	a device used for scratching
someone who is willing to trade favors or services for mutual advantage	a person who scratches to relieve an itch
	a workman who uses a tool for scratching