Whats the difference between a work of art intended for documentation and one intended for commemoration.

A work of art intended for documentation is always an historical and factual account of a person, place or event. Documentation provide evidence that an event occurred, thus a work of art intended for documentation provide evidence for events in history.
A work of art intended for commemoration serves principally as a memorial or a mean to remember a thing, person or an event. It stands as a form of remembrance rather than mean of documentation.

The answer is all of the above.