sham vs ringer

sham and ringer both are nouns.

Word	Noun	Adjective	Verb	Adverb
sham	Yes	Yes	Yes	No
ringer	Yes	No	No	No

As nouns, ringer is a hyponym of sham; that is, ringer is a word with a more specific, narrower meaning than sham:

Other hyponyms of sham include name dropper.

sham (noun)	ringer (noun)
something that is a counterfeit; not what it seems to be	(horseshoes) the successful throw of a horseshoe or quoit so as to encircle a stake or peg
a person who makes deceitful pretenses	a contestant entered in a competition under false pretenses
	a person who is almost identical to another
	a person who rings church bells (as for summoning the congregation)

sham (adjective)	ringer (adjective)
adopted in order to deceive

sham (verb)	ringer (verb)
make believe with the intent to deceive
make a pretence of