Question

The Giant Planets are now split into two groups - Gas Giants and Ice Giants. What is the difference between the two groups? Which planets are in each group?

Answer 1

The “gas giants” Jupiter and Saturn are mostly hydrogen and helium. These planets must have swallowed a portion of the solar nebula intact. The “ice giants” Uranus and Neptune are made primarily of heavier stuff, probably the next most abundant elements in the Sun – oxygen, carbon, nitrogen, and sulfur.

Diffrence

Gas giants are primarily composed of gases, such as hydrogen and helium, and a much thicker layer of metallic hydrogen, along with a molten rocky core. ... As of now, there are only two gas giants in our solar system – Saturn and Jupiter. Uranus and Neptune are now known as “ice giant

Gas Giants consist primarily of the gases hydrogen and helium, with a rocky/iron core.

The interiors of Ice Giants consist primarily of what astronomers call 'Ices'. These are compounds like water, methane and ammonia, and are so-named presumably because they are solid at cold (-200 C) temperatures, unlike hydrogen and helium, which remain gaseous up until very close to Absolute Zero.

Hydrogen and helium are very light, and it only takes a small amount of heat energy to make them fast enough to escape the gravitational field of most planets. Jupiter and Saturn are the only planets heavy enough to retain a significant fraction of hydrogen and helium (though the atmospheres of ice giants Uranus and Neptune consist mainly of hydrogen and helium, it's mainly ices further down