episode vs instalment

episode and instalment both are nouns.

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

As nouns, episode and instalment are synonyms defined as:

Other synonyms of episode include installment.

episode (noun)	instalment (noun)
film consisting of a succession of related shots that develop a given subject in a movie	the act of installing something (as equipment)
a part of a broadcast serial	a part of a broadcast serial
a brief section of a literary or dramatic work that forms part of a connected series	a part of a published serial
a happening that is distinctive in a series of related events