The difference between perfume and eau de parfum is that perfume is more concentrated than eau de parfum. This also makes perfume more expensive than eau de parfum. Perfume is often used as a base for eau de parfum.
Perfume contains a higher concentration of essential oils than eau de parfum. Essential oils are expensive and difficult to extract. Other ingredients that often make up perfume are alcohol and water.
Because it's so concentrated, perfume is applied conservatively to particular parts of the body, such as the pulse points and behind the person's ears. Eau de parfum, on the other hand, can be sprayed on freely.