Essential oils are highly concentrated plant extracts (usually steam distilled) and are used in aromatherapy applications.
The highly volatile essential oils offer therapeutic value and natural scent choices.
For use in soap making, the scent does not last as long as a fragrance oil. Essential oils as a rule should be diluted before using on the skin.
A patch test is always recommended before applying neat on the skin.

Fragrance oils are designed by the perfume industry for use in cosmetics and other household/industrial applications.
They offer a wider variety of scents, often less expensive than essential oils (such as rose, jasmine, violet, etc.).
Fragrance oils have more “staying power” in terms of scenting soaps & cosmetics.