Where did cometary water come from and why do comets have more water than Earth?

[Vrbic]

A big part of water on Earth come from comets at the very early ages of Earth so I suppose that the comets has same age as the Earth. The Earth and other objects come from a waste after creation of the Sun. The Sun come from cloud of hydrogen and helium mostly. It is star of 3rd-generation so I suppose some other elements were present. If you disagree with anything let me know.
I have two questions:
1) Why does the comets have more water than Earth? I mean percentually.
2) Where did the water that forms the comets come from?

 

[Drakkith]

1) Why does the comets have more water than Earth? I mean percentually.

Comets formed in the outer solar system where the Sun's light and heat couldn't prevent water molecules from forming large quantities of ice. The inner solar system is too warm for ice to form (except on already existing planets where there are ways of transporting heat away from the ice and keep it insulated against the heat from the Sun, along with an atmosphere to keep it from sublimating away into space).

2) Where did the water that forms the comets come from?

It was present as oxygen and hydrogen in the initial gas and dust cloud that ended up forming the solar system.

 

[Vrbic]

Comets formed in the outer solar system where the Sun's light and heat couldn't prevent water molecules from forming large quantities of ice. The inner solar system is too warm for ice to form (except on already existing planets where there are ways of transporting heat away from the ice and keep it insulated against the heat from the Sun, along with an atmosphere to keep it from sublimating away into space).

It was present as oxygen and hydrogen in the initial gas and dust cloud that ended up forming the solar system.

Ok, thnak you.