Are you sure? Octopi are molluscs, while polyps are cnidarians (such as coral and sea anemones)
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The two Phylums may have some superficial similarities but are quite distinct.
Well, I'm not a marine biologist, I don't know the difference. I just tried to translate it as best as possible. The general public doesn't know the difference anyways, for them it's the same. When they hear "octopus" or "polyp" they think about sea monsters with tentacles. And I don't think TLC has thought about biological subtleties, either, when they chose the name ;-)