This question is a bit tricky because it's phrased in a way that's easy to misunderstand. Here's the breakdown:

* Water (H₂O) has two hydrogen atoms and one oxygen atom.

* Hydrogen (H₂) is a molecule made up of two hydrogen atoms.

So, to answer your question directly:

* Hydrogen (H₂) has zero oxygen atoms.

* Water (H₂O) has one oxygen atom.

Therefore, hydrogen has one less oxygen atom than water.

It's important to remember that the question is asking about the number of oxygen atoms in each molecule, not about how many more hydrogen atoms water has compared to hydrogen.