https://en.wikipedia.org/wiki/Gas_giant:

> However, in the 1990s, it became known that Uranus and Neptune are really a distinct class of giant planets, being composed mainly of heavier volatile substances (which are referred to as "ices"). For this reason, Uranus and Neptune are now often classified in the separate category of ice giants.[2]

I guess there's a distinction I wasn't aware of.

Edit: I had this comment written, but I guess I waited too long to submit.