I thought they were the same plant, too. But
I just got mine this spring, and the friend who gave it to me said it was Tea Cups. I have two divisions growing in my pond, and two more in pots out in the back yard. I really expected them to take off and get huge with all the rain we had, but they didn't. I fertilized them and everything! They are less than 3ft. tall and the biggest leaf is maybe 10in. long.
So, maybe there is a dwarf variety going around, or maybe Tea Cups is a smaller version of Coffee Cups? Or maybe it will take off and get huge next year in a bigger pot?
Sorry Sway, this was pretty much no help at all.