You can find essential oils in the natural food section of stores. They usually come in limited scents that are rather strong and bitter in scent, save for a few such as citrus and peppermint. This is because the process for producing essential oils limits the kinds of plants from which an essential oil can be produced.
Oils for skin and home fragrance (oil diffusers) are often made of “fragrance oils.” Fragrance oils have the chemical structure of other oils, but instead of being extracted from a plant, they are engineered in a lab by chemists to smell like certain things. This is why vanilla fragrance oil exists, but vanilla essential oil does not. It is not possible to extract an essential oil from a vanilla plant, but it is chemically possible to mimic a vanilla smell.
I personally prefer fragrance oils because they more readily come in more perfume-like scents, such as non-citrus fruits. You can buy fragrance oils at shops like the Body Shop, candle making stores, and soap making stores.
And, of course, you can find all sorts of essential oils and fragrance oils online, as well!
Essential oils and fragrance oils both last the same amount of time and have a similar range of uses. So which you prefer—unless you need a specific essential oil for, say, antibacterial purposes, et cetera—will depend entirely on what kind of scents tickle your nose the most!
I hope this was helpful!
– KJ