by-product vs effect

by-product and effect both are nouns.

Word	Noun	Adjective	Verb	Adverb
by-product	Yes	No	No	No
effect	Yes	No	Yes	No

As nouns, effect is a hypernym of by-product; that is, effect is a word with a broader meaning than by-product:

Other hypernyms of by-product include consequence, event, issue, outcome, result, upshot.

by-product (noun)	effect (noun)
a product made during the manufacture of something else	an outward appearance
a secondary and sometimes unexpected consequence	(of a law) having legal validity
	an impression (especially one that is artificial or contrived)
	the central meaning or theme of a speech or literary work
	a phenomenon that follows and is caused by some previous phenomenon
	a symptom caused by an illness or a drug

by-product (verb)	effect (verb)
	produce
	act so as to bring into existence