The difference between SERUMS/ESSENCE/AMPOULES
Serums are lightweight moisturizers that penetrate deeper to deliver active ingredients into your skin. Serums contain a few key active ingredients to address specific issues like brightening, dark spots and wrinkles etc. Because serums are typically very concentrated, a little goes a long way.
Essence and Serums is one of the same thing. Both essence and serums are used at the same step of your skin care routine to achieve similar results. You are very likely to notice a small difference in the product textures.
Ampoules is a supercharged serum with a higher concentration of active ingredients that you are meant to use for a limited time as a booster or when you are having a skin crisis of some sort. It is recommended you use an ampoule before your essence or serum, if you intend to combine this into your skin care regime.