nightrider vs attacker

nightrider and attacker both are nouns.

Word	Noun	Adjective	Verb	Adverb
nightrider	Yes	No	No	No
attacker	Yes	No	No	No

As nouns, attacker is a hypernym of nightrider; that is, attacker is a word with a broader meaning than nightrider:

nightrider: member of a secret mounted band in United States South after the American Civil War; committed acts of intimidation and revenge
attacker: someone who attacks

Other hypernyms of nightrider include aggressor, assailant, assaulter.

nightrider (noun)	attacker (noun)
member of a secret mounted band in United States South after the American Civil War; committed acts of intimidation and revenge	someone who attacks