Fragrance goes by so many different terms—perfume, parfum, eau de parfum, eau de toilette—that it can be confusing to figure out which one to buy. The key to choosing the right scent for you is knowing that the different terms refer to different concentrations of fragrance oils in the mix.
Historically, France is the biggest exporter of fragrance, particularly in the Occitane region, which is home to many fragrant herbs, such as lavender. We continue to use French terms today. There is virtually no difference between perfume and parfum. Parfum is the French term for perfume, so they can be used interchangeably. But these should not be confused with eau de parfum, which is a different product.
Scents (e.g., lavender or sandalwood) are the essential oils that give perfume its fragrance, which are mixed together with fixatives and solvents like alcohol and water. Of all the different types of scents, perfume, or parfum, contains the highest concentration of these oils (between 20 percent and 40 percent) so they linger longer on the body, and require you to apply less.
Eau de parfum, on the other hand, contains a lower concentration of these oils, as does eau de toilette (between five percent and 30 percent). You may prefer these products, especially if you have allergies, because they're less overpowering than other products, but you may need to re-apply them more often in order for the scent to last.
Other fragrance products, such eau de cologne, aftershave or scented hand lotion, are often used by men who prefer a less-potent scent. These typically contain around one percent or two percent essential oils.
Whether you call it perfume or parfum, when you buy a product with a high concentration of essential oils, you don't have to reapply it as often, so it lasts much longer. Though these products are often more expensive, in the long run they can save you money and leave you smelling lovely.