Explain the terms " terrestial planets" and " gas gaints"

The terestrial planets is explaining the first four planets which are mercury, venus, earth, and mars. They have land/rocks on them, so you can stand upright on those planets. The gas giants are the last 4 planets, which are Jupiter, Saturn, Uranus, and Neptune. Meaning that if you were to stand up right on the surface of those planets you would keep falling and never touch a hard surface, due to the fact that they are full of gas