The difference between perfume and cologne is dependent upon lower or higher concentrations of the oils that make up the fragrance. Pure perfume has the highest concentration of oils, followed by eau de parfum, eau de toilette and eau de cologne. Traditionally, cologne and perfume were interchangeable in terms of fragrance; however, through time, the term perfume has come to be associated with women and cologne with men.
Pure perfume is a mixture of essential oils and ethanol (alcohol) and results in a strong fragrance. It's expensive, highly concentrated and usually sold in very small bottles. In the early 20th century, perfumeries started to market to a larger crowd by creating more affordable, less concentrated forms of their scent referred to as eau de parfum, eau de toilette and eau de cologne. Aftershaves, splashes and sprays are the most diluted forms of scent.
Most scents marketed as perfumes or colognes today are actually versions of eau de parfum or eau de cologne. Eau de toilette or eau de cologne marketed towards men are infused with spicy, earthy masculine scents such as rosewood, citrus, and fresh laundry. Eau de parfum is considered feminine with sweet fragrances such as lavender, vanilla, floral scents and cinnamon.