A thread about categories? Must be the place for me!
My first thought is that the division into "tarot" and "oracles" meaning every other kind of divination cards is a conventional one allows us see quickly whether a deck of cards has a tarot structure or something else. "That deck with 52 cards isn't really tarot, it's (just?) an oracle deck!" It's possible that this conventional meaning was perpetuated mostly by this site . . .
Then lenormand became more popular, bringing its own division here on Aeclectic.
I agree that technically, in the English definition sense, anything used for divination, including people, can be called oracles. But we can narrow it down a good bit by saying "oracle cards." Again, in a technical sense, tarot would be oracle cards, as would playing cards, if used for divination.
But if, with the rise of lenormand, the term oracle cards is beginning to/will be used only for decks of cards with unique, creator-invented systems (or no system at all, just a bunch of keywords, with or without a unifying or limiting theme (animals, goddesses, etc.)), I would suggest that we need another category, one for decks of cards based on non-card divination systems: I Ching, astrology, runes, numerology, palmistry, mah jong divination, etc.
But in what category would playing card divination go?
And what about divination decks based on esoteric systems that aren't usually used for divination, like Hebrew letters, 72 names of God, chakras, etc.?
Just throwing it all out there. What do you think? In reality, we, the members of this site, are probably the most influential innovators and arbiters of divination terminology, so we might as well take some time to think about it!