chapter vs episode

chapter and episode both are nouns.

Word	Noun	Adjective	Verb	Adverb
chapter	Yes	No	No	No
episode	Yes	No	No	No

As nouns, episode is a hypernym of chapter; that is, episode is a word with a broader meaning than chapter:

chapter (noun)	episode (noun)
a subdivision of a written work; usually numbered and titled	film consisting of a succession of related shots that develop a given subject in a movie
a series of related events forming an episode	a part of a broadcast serial
a local branch of some fraternity or association	a brief section of a literary or dramatic work that forms part of a connected series
an ecclesiastical assembly of the monks in a monastery or even of the canons of a church	a happening that is distinctive in a series of related events
any distinct period in history or in a person's life