'Preternatural' vs 'supernatural'

I am wondering what the precise differences between preternatural and supernatural are.

I know praeter is Latin for beyond so that preternatural literally means beyond natural. But how exactly does that compare to supernatural? Isn't supernatural just the same thing?

I also have the vague idea that on the "scale of unnatural-ness" we should have

unnatural < preternatural < supernatural = most unnatural.

Is that the only distinction?

Preternatural is a wonderful word, one that's been saved from being overused only by the fact that no one seems to know what it means.

It means "apparently inexplicable by natural means". You might say, "Yo Yo Ma is a praeternaturally skillful cellist" (bonus points for the olde-timey spelling), meaning only that he is really, really ridiculously good. You aren't claiming that he's actually, non-metaphorically magical or ghostly. Yo Yo Ma does exist. (I know for sure: I saw him once, at a CostCo of all places. I was going to talk to him, but all I could think of to say was "Hey, is it true you once left a Stradivarius on the plane? FAIL!")

Supernatural is pretty much a dumb word. People use it for ghoulies and ghosties and long-legged beasties and things that go bump in the night — i.e., things that, unlike Yo Yo Ma, do not exist. Why people feel the need to divide non-existent entities into subcategories I don't know.

To use one of James Randi's old examples: if in fact Uri Geller's claimed ability to bend spoons with his mind actually existed, that would be supernatural; in reality, his ability to bullshit people is preternatural.

Preternatural means uncanny, unexplained in nature, but of this world (for example might have preternatural hearing without anything unnatural or supernatural happening).

Supernatural means something uncanny in nature, and not of this world (for example supernatural hearing would be hearing enhanced by magic or ghosts or somesuch supernatural thing).

Edit: The above is consistent with (but not a quotation of) the definitions in the OED.