chemical plant vs manufactory

chemical plant and manufactory both are nouns.

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

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

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

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

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