The main difference between types of fragrance lies in the concentration of essences. The order of highest to lowest concentration is first Perfume, second, Eau de Parfum, third, Eau de Toilette, and fourth Eau de Cologne.
Perfumes are classically defined as a combination of top, heart, and base notes released over a period of time. The top notes are the first scent released by a fragrance. After the top notes have faded, the middle or heart notes of a fragrance become noticeable.
Perfume is considered the most beautiful form of fragrance because it releases the top, heart, and base notes over a period of time, as opposed to one faster than the other (due to its high concentration of essences). With Eau de Parfum, the heart (middle) notes become noticeable after the top notes have faded away. Conversely, with Eau de Toilette, the top notes, the first scent released, are dominant. This makes it initially very refreshing, and it then evaporates rather quickly.
Perfume is very expensive because it can have up to 40% concentration of essences. This means that the scent is released over a long period of time, and therefore much less is needed and is sold in much smaller volumes.
Eau de Parfum contains up to 15% perfume concentrates, and Eau de Toilette contains up to 10% perfume concentrates. One could think of Eau de Parfum as a bit heavier and long-lasting than Eau de Toilette. Eau de Parfum is also often used on hair and clothing, however one must be careful with delicate fabrics as they could stain due to the oils. Some of the more prestigious and delightful Eau de Parfums are Hermes ' 24 Faubourg', a distinguished, floral scent with hints of amber, or Issey Miyake ' L'eau d'Issey Florale', a feminine floral blend of lily, orange blossom, mandarin, rose, musk and white wood.
Eau de Toilette, on the other hand, with up to a 10% perfume concentration, is a lighter, more refreshing scent, and very suitable particularly for warmer climates. Eau de Toilette, however, does fade away a bit faster than Eau de Parfum. A good example of a classic Eau de Toilette is the quintessential ' Eau d'Hadrien' by Annick Goutal -a fresh breath of the Mediterranean - with its fresh citrus fruit combination of lemon, grapefruit, green mandarin, cypress, and ylang ylang. Another rather opposite scent would be Jean Paul Gaultier's ' Classique', which more embodies the sexiness of a woman through its combination of rose, star aniseed, orange, ginger, amber and vanilla.
Typically Eau de Parfum is more expensive than Eau de Toilette due to the higher concentrations of essences contained therein. Both Eau de Parfum and Eau de Toilette are sold in medium volume as one needs to use more than perfume.
And lastly, Eau de Cologne, has up to a 7% perfume concentration. It is refreshing for hotter climates and can be reapplied as needed due to the speedy evaporation. Eau de Cologne is sold in larger lots and tends to be the least expensive perfume.