Both movies are the same story; a learning disabled man faces some prejudice from his co-workers and mother. He is then given the opportunity to become smarter through an operation.
Algernon Ni Hanataba O has more of a romantic focus, and the main character's transformation from dumb to smart is much more dramatic, while Algernon Ni Hanatabo Wo spends more time showing the main character's struggle while he is learning disabled.

Both are the same story about a mentally disabled man who is made smarter through modern technology.

Ichi 1: Origin is the origin story of Ichi from Ichi The Killer. Ichi is played by the same actor in both films.

Both movies show the harsh conditions of a Filipino jail. They also explore homosexual love between inmates.

Both movies are about juvenile delinquets running amuck and causing trouble.

Both are Filipino movies about a young man having a rough go in prison.

Incomplete Life is the original story. Misaengmul is a parody of it.

Hope is the japanese version of the same story.

Incomplete Life is the original. The Ordinary Glory is the chinese adaption.

Both share the theme of domestic abuse and are quite graphic in their depiction of it.

Both have the same plot. A doctor uses hypnosis to manipulate one of his patients into sleeping with him.

Both movies show men suffering in prison for their political beliefs. Although, National Security is much more graphic.