Essence / Serum
Essence is a skincare product which is made of polymer extracts concentrated nutrients. It might be based on water or oil.
The feature of essence is small molecule, pure ingredient and high concentration, which could lead the nutrients deep down to skin.
There is no obvious difference between essence and serum. In general, essence is aqueous; serum is oily. Essence is with nutrients to improve overall skin quality, the main purpose is anti-aged; Serum is specific to certain skin issue, such as stain, wrinkle, dull, etc.