I guess I never thought about it close enough to distinguish between "variations", "varieties" or "errors". From my perspective, I only knew (or thought) they were different.

In most cases, I do not know enough about chip release dates to help me determine if they are different releases, or variations of the same release.

As far as the Regency chips you scanned, I would likely have never noticed, but they are different (and if I collected $20's, I would seek out 1 of each).