Direct continuations of a previous story.

Direct precursors of a previous story.

Conversion of a story to a different medium.

Re-writes of an existing story with the implication of accuracy.

Re-writes of an existing story which explicitly diverge.

Re-writes of an existing story without implicit accuracy. Though this can also be considered a meta-category for remakes and reimaginings.

A stand-alone or spin-off which takes inspiration from an existing story but which makes no promise or attempt to remain accurate. Accuracy is coincidental.