Well... on a molecular level, yes. [Someone had been learning science!] They are both comprised of the same elements and the same ratio of elements. It's just the temperature that makes it change state. That's why, when you pour water over ice, the ice melts into more water. Especially when the ambient temperature around you is higher than that of the ice. [Romelle liked learning.]

So, yes... I suppose it would stand to reason that Water types have the advantage. Fire types would, as well. But ice is strong against grass, as we've all seen what an early or late frost can do to a garden.