Normal Oxides:

The Oxides in which oxidation state of central atom is found to be one of the it's common oxidation state. The are also called acid anhydrides because on dissolving them  into water oxygen acid is formed in which oxidation state of central atom is found to be same as present in Oxide.

Examples:  B₂O₃, CO₂, N₂O₃, N₂O₅, SO₂, SO₃, Cl₂O₇, XeO₃, XeO₄ etc.

Peroxides

The oxides in which  calculated oxidation state of central atom is more than maximum oxidation state of central atom due to the presence of peroxide linkage.

For examples, H₂O₂, Na₂O₂, BaO₂, PbO₂, CrO₅ etc.