Serums are lightweight concentrated liquids that contain antioxidants and anti-inflammatories to target specific skin concerns. They have small molecules that allow them to absorb deeply into the skin.
Face oils are often oil-based liquid formulations that are made up of non-comedogenic botanical oils. These oils primarily nourish, protect and moisturize the skin and don't cause breakouts or clogged pores.
Serums are one of the first products to use therefore it sits under your moisturizer. Whereas face oils lock in moisture therefore, they sit on your moisturizer.
The overall goal of both the serum and the face oil is that they aid the overall health of your skin.