The difference between cologne (eau de cologne) and eau de toilette is the concentration of essential oils that the solutions contain. Eau de cologne traditionally contains a concentration of 2 to 8 percent perfume oil, while eau de toilette contains a concentration of 5 to 15 percent perfume oils.
Fragrances are divided into several categories based on the overall concentration of essential or perfume oils contained in the product. The concentration of perfume oil affects the overall longevity of the odor and the cost of the product. Aftershave is the weakest men's fragrance. It contains 1 to 2 percent perfume oil. Aftershave is the cheapest men's fragrance, and the odor typically lasts for only a short period of time.
Eau de cologne contains a concentration of 2 to 8 percent perfume oil. It is a low-cost product, and the fragrance typically lasts for one to two hours before it has to be reapplied.
Eau de toilette contains a concentration of 5 to 15 percent perfume oil. The odor lasts anywhere from three to six hours. It is one of the most popular types of men's fragrances as of 2015.
Eau de parfum contains a concentration of 10 to 20 percent perfume oil. The odor lasts anywhere from six to eight hours. This is the most popular type of women's fragrance.
Extrait de parfum contains 15 to 40 percent perfume oil. The odor can last over eight hours.
Attar is pure perfume oil. It does not contain any alcohol or water. A small amount of this type of fragrance can last over 12 hours.