environmentalist vs reformer

environmentalist and reformer both are nouns.

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

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

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

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

environmentalist (noun)	reformer (noun)
someone who works to protect the environment from destruction or pollution	an apparatus that reforms the molecular structure of hydrocarbons to produce richer fuel
	a disputant who advocates reform