environmentalist vs crusader

environmentalist and crusader both are nouns.

Word	Noun	Adjective	Verb	Adverb
environmentalist	Yes	No	No	No
crusader	Yes	No	No	No

As nouns, crusader is a hypernym of environmentalist; that is, crusader is a word with a broader meaning than environmentalist:

environmentalist: someone who works to protect the environment from destruction or pollution
crusader: a disputant who advocates reform

Other hypernyms of environmentalist include meliorist, reformer, reformist, social reformer.

environmentalist (noun)	crusader (noun)
someone who works to protect the environment from destruction or pollution	a disputant who advocates reform