Neptune is ‘only’ 57 times the volume of Earth, whereas Jupiter is 1321 times the volume of Earth. The size range of ice/gas giants is bigger than the gap between Earth and the smallest ice giants.

Does it make sense to compare both Neptune and Jupiter to the Earth? I would think the relative numbers for each pair are a more useful comparison.

If Neptune is 57 times the volume of Earth and Jupiter is 1321 times the volume of Earth, then Jupiter is 23 times the volume of Neptune.

So the relative difference between Neptune and Jupiter is less than half the relative difference between Earth and Neptune.

As another illustration, let's take a different trio of objects: a golf ball, the Moon, and the Earth.

Using very round numbers, it is safe to say that the volume of the Moon is about one zillion golf balls.

The Earth is about 50 times the volume of the Moon, so the Earth is 50 zillion golf balls.

Clearly, the difference between 50 zillion and 1 zillion is much greater than the difference between 1 zillion and just 1 golf ball, by a factor of nearly 50.

Or is it? If you ask anyone on the street, they won't have to calculate anything, they will tell you that the Earth and Moon are much more similar in size than the Moon and a golf ball. That's because they are using relative sizes, not absolute.