Essentials Oils are lightweight, evaporates quickly, and mostly used to treat the hair. Carrier Oils are oily and can be from different veggies, fruits, and nuts. You can use it for moisturizing. Essential oils are normally mixed with carriers oils.
I won't go into full details about oils but here are a few popular ones
Tea Tree Oil
When I was relaxed I mostly used castor oil, I would apply it to my DAX grease. I use tea tree oil for my nose ring to help with the healing process. Oils can be use in different ways. Everyone has a different way they use oils. Hot oil treatments. You can apply them to dry or wet hair. I personally use the first three on my hair. I moisture my hair by mixing the three oils plus water in a spray bottle and apply it the hair. I spray my hair after washing, while styling, and when it gets dry.
What I'm using
Queen Helene Jojoba Oil, Pompeion EVOO, Organic Coconut Oil
My spray bottle