- H2O is the chemical formula for water, a molecule composed of two hydrogen atoms and one oxygen atom. Water is a colorless, odorless, and tasteless liquid that is essential for life. It is the most abundant substance on Earth's surface and makes up about 70% of the human body.

- H2O2 is the chemical formula for hydrogen peroxide, a molecule composed of two hydrogen atoms and two oxygen atoms. Hydrogen peroxide is a pale blue, slightly viscous liquid with a pungent odor. It is a strong oxidizing agent and is used as a bleaching agent, disinfectant, and antiseptic.

While both H2O and H2O2 contain hydrogen and oxygen atoms, they are different molecules with different properties and uses.