Much of the difference between grapefruit essential oil and grapefruit extract starts with the way they're processed. Essential oils go through more rigorous processing than grapefruit extract, in which they’re converted to therapeutic strength. Grapefruit essential oil is used in massages, yoga, mindfulness activities, and aromatherapy. Grapefruit extracts, on the other hand, are used as supplements for your health. It’s always a good idea to ask your doctor before you use grapefruit oil or extracts.