This page will help to illucidate the differences and similarities for you. Not acceptable in the United States, but a popular category in Europe and elsewhere in the world. Oleoresins Oleoresins are pure extractives of a spice or herb. Oleoresins provide flavor profiles characteristic of the ground spice or herb with a more rapid flavor release. They provide ease in handling and measuring.
Oleoresins are soluble in oil.
They provide the aroma profile of the ground material, without the non-volatile portion. Essential Oils are typically clear in appearance. Essential Oils are soluble in oil. These products are dry powders made of oleoresins and essential oils encapsulated in protective coatings of modified food starch, maltodextrin or gum arabic. These concentrated flavors are very versatile and work well in dry and aqueous based systems.