The main difference is how concentrated the actives are: essence is the lightest and most diluted, serum sits in the middle, ampoule is the most concentrated. They are not three categories with different jobs — they are three degrees of the same thing, and they occupy the same place in a routine: after toner, before cream.
Essence
Watery texture, almost like a slightly thicker toner. You pat it in with your hands rather than rubbing. In the Korean tradition it is the step that prepares skin for the treatments that follow, and for many people it is the product that defines K-beauty.
In stock you'll find Beta-Glucan Essence by Mixsoon, Reishi Mushroom Essence and the two VT Reedle Shot essences, which come in two strengths. The rest are in essences.
Serum
This is the targeted treatment step: more concentrated than an essence, with a texture anywhere from watery to slightly velvety. You pick one for a specific need, not "in general".
A few from the catalogue, with what each product page states: Glow Propolis + Niacinamide by Beauty of Joseon with propolis and niacinamide; Dark Spot Correcting Glow by Axis-Y; Snail Truecica Miracle Repair by Some By Mi, built on snail mucin. The rest are in serums and ampoules.
Ampoule
The most concentrated version. Korean practice tends to use them in cycles — a few weeks when skin needs something more decisive — rather than every day forever. The bottles are usually smaller for exactly that reason.
The four Esfolio ampoules in stock cost €9.90 and cover four different needs: hyaluronic acid, centella, retinol and vitamin.
Do you need all three?
No. Most routines need one, and for anyone starting out a serum is the sensible pick: it is the compromise between strength and tolerability.
Using two makes sense when they treat different things — a hydrating essence in the morning, a targeted serum at night. Layering three with similar actives does not multiply the result: it only raises the odds of irritating your skin.
What order, if you use more than one
The general rule applies: thinnest to thickest. So essence, then serum, then ampoule, then cream. Waiting for each layer to absorb before the next one is worth it — a minute is enough.
The full sequence is in what order to apply skincare in.