[MinusGix]

You could frame it as discovery being finding something out about the thing. So you find out the color of the trees in fall, the sun that an asteroid is about to fall into, or a person's name. For invention, you are usually deliberately creating it. Your composer works on the music to become better, and chooses better chords to play. The programmer modifies his code to fix an issue he noticed, thus making the invention better.

I think they are separate. Even if they are 100% related, all from the same factors of psychology, it would still be useful to differentiate them.