Most people assume eau de cologne (or cologne), eau de toilette, eau de parfum and perfume are one and the same thing, and often use them interchangeably. But there are, in fact, a few key differences between them. Colognes and eau de toilettes are lighter and more suited for warmer weather. They also tend to wear off sooner than eau de parfum and perfume, which are heavier, last longer and are more suited for colder weather.
They differ in the concentration of the essential oils they contain, leading to a difference in the strength of the scent. Colognes typically have about a 2-5% concentration of essential oils, and eau de toilettes a concentration of about 7%, and are therefore lighter fragrances in comparison to perfumes or eau de parfums which typically have a concentration of 15% or more.
Many people consider perfumes more beautiful scents than colognes, owing to their complexity. While the lighter fragrances are usually built around a single scent, perfumes or eau de parfums give you a more layered fragrance that changes through the day. Most perfumes have a top note- the scent that hits you soon after application, a middle note and base note- which kick in once the top note fades away, creating beautifully layered scents. But, nothing can be as refreshing as the scent of the fresh top notes of a cologne or an eau de toilette on a warm day- moreover, these can be reapplied through the day since they tend to wear off much sooner than perfumes.
Colognes are cheaper than their perfume variants, because of their lower concentration, and come in larger bottles than perfumes. And while just a little dab of perfume on your wrists, behind your ears, or at the nape of the neck should do, colognes can be sprayed on more generously.
But the most important part of choosing the right fragrance is still all about finding one that makes you feel and smell wonderful.