pilferer vs stealer

pilferer and stealer both are nouns.

Word	Noun	Adjective	Verb	Adverb
pilferer	Yes	No	No	No
stealer	Yes	No	No	No

As nouns, stealer is a hypernym of pilferer; that is, stealer is a word with a broader meaning than pilferer:

pilferer: a thief who steals without using violence
stealer: a criminal who takes property belonging to someone else with the intention of keeping it or selling it

Other hypernyms of pilferer include thief.

pilferer (noun)	stealer (noun)
a thief who steals without using violence	a criminal who takes property belonging to someone else with the intention of keeping it or selling it