Essential Oil vs Fragrance Oil

Essential oils are obtained by extracting contents directly from certain plants, roots, herbs and flowers. Even though they are pure and natural, they do not contain any vitamins because there is no fat/lipid or water content for the vitamins to be sustained. The major benefit of essential oils is the aroma and purity of the scent. The aroma can promote mental health and clarity whilst also clearing sinus, destress, sooth and calm a hyperstimulated mind. 

Fragrance oils are man made, synthetic imitations of a flower, plant, root, herb or food item people wish to have as an everyday scent. They're long lasting and potent and can be used in almost every area of living for all sorts of reasons (laundry, diffusers, room spray, body spray etc.). These scents are created by using a range of chemicals and methods. there is also a large market for 'flavour oils' which are safe to ingest and often used in sweets. 

Chemicals & Allergies
Both essential oils and fragrance oils come with risk for allergic reaction.
Firstly, the essential oil has chemicals created by nature and therefore if a person is allergic to pollens, fibers etc. of that plant it can cause a skin reaction or a sinus allergy; the reaction can develop quite quickly after first exposure or gradually with continued use.
Secondly, fragrance oils contain a mix of synthetic chemicals that can cause a skin reaction, irritate eyes and sinus when inhaled at large or prolonged volumes and are no more or less a risk than essential oils.
Therefore, it is important to ask, just incase, what fragrance or essential oil is being used in the product you want to buy so you can determine if it is what is best for you. 

Link: Essential oils explained https://www.healthline.com/nutrition/what-are-essential-oils#benefits