An ampoule is a supercharged serum with higher concentrations of active ingredients that you're meant to use for a finite amount of time as a booster or when you're having a skin crisis of some sort. Typically used before your apply your serum.
Who doesn't love a good face serum. Especially in the cooler months for that extra skin hydration.
Serums contain the most potent dose of anti-aging ingredients -antioxidants, peptides, and skin brighteners such as kojic acid -- you can find in nonprescription products.
You just need a few concentrated drops for serums to work quickly and effectively. Serums are made of very small molecules, so the skin absorbs them quickly and deeply.
The main difference between serums and oils is that oil molecules are much larger and serve to penetrate only the outermost layers of the skin. Despite oil's inability to penetrate the skin further, oils still work to provide essential ingredients that help to nourish the skin.