A literary form in which one story is told in the guise of another story is called -

Allegory: (রূপক বর্ণনা; প্রতীকাশ্রয়ী কাহিনী)
A literary form in which one story is told in the guise of another story.
Ex: Bunyan's Pilgrim's Progress

Novelette:
A short novel usually of thirty to forty thousand words. It is shorter than a novel but longer than a short story.
Non-fiction:
Fictitious narratives in prose.
Satire:
A literary attack on the follies and vices of an individual or a society with a view to correcting them through laughter and ridicule is known as satire. It may be in prose or in verse.

Source: An ABC of English Literature by Dr. M Mofizar Rahman.