word choice - What's the difference between direction and orientation?

I frequently see these two words in 3D programming. For example:

the direction of the directional light

the orientation of camera

So, what’s the difference between them?

Answer

I think that the words are very similar, but there is arguably a subtle distinction.

The word direction suggests movement. While it may refer to a static object, it describes it as if it were or could move toward the described location.

the position toward which someone or something moves or faces:
Cars were facing every direction after slamming into each other on the icy road.
I glanced in her direction (= toward her).
You’re headed in the direction of (= toward) Toronto.

The word orientation seems to connote that the object is static and there is no suggestion of movement. As noted in a comment to this post, it is a relationship to the environment.

the position of something in relation to its surroundings:
The church has an east-west orientation (= has one main side facing east and the opposite side facing west).

There are many cases where either could be used, (even a paraphrase of one of the examples under direction)

Cars were oriented every which way after slamming into each other on the icy road.

However, there are many when only one or the other will do.

He moved in the direction of the door.
His orientation allowed him to see the window while lying prone.

A substitution probably could be made, but it would call for a more convoluted sentence.