raider vs thief

raider and thief both are nouns.

Word	Noun	Adjective	Verb	Adverb
raider	Yes	No	No	No
thief	Yes	No	No	No

As nouns, thief is a hypernym of raider; that is, thief is a word with a broader meaning than raider:

raider: someone who takes spoils or plunder (as in war)
thief: a criminal who takes property belonging to someone else with the intention of keeping it or selling it

Other hypernyms of raider include stealer.

raider (noun)	thief (noun)
a corporate investor who intends to take over a company by buying a controlling interest in its stock and installing new management	a criminal who takes property belonging to someone else with the intention of keeping it or selling it
someone who takes spoils or plunder (as in war)