chemical plant vs factory

chemical plant and factory both are nouns.

Word	Noun	Adjective	Verb	Adverb
chemical plant	Yes	No	No	No
factory	Yes	No	No	No

As nouns, factory is a hypernym of chemical plant; that is, factory is a word with a broader meaning than chemical plant:

chemical plant: an industrial plant where chemicals are produced
factory: a plant consisting of one or more buildings with facilities for manufacturing

Other hypernyms of chemical plant include manufactory, manufacturing plant, mill.

chemical plant (noun)	factory (noun)
an industrial plant where chemicals are produced	a plant consisting of one or more buildings with facilities for manufacturing