The differences are the amount or concentration of oils in the fragrance.
- Pure Perfume - 15-30% aromatic compounds
- Eau de Parfum - 10-15% aromatic compounds
- Eau de Toilette - 5-20% aromatic compounds
- Eau de Cologne - 2-5% aromatic compounds
Some manufacturers make a solid perfume, solid perfume is as strong as a pure perfume however it is in a gel-like consistency.
Eau De Toilette and Eau De Cologne are generally interchangeable, especially in Men's fragrances. After Shave has the least amount of oils. The higher the concentration the longer your fragrance will last, and the less you need to apply.