Ampoule or Serum?

I believe the terms can by used synonymously with one another but I think an ampoule will be much more concentrated/potent. That is my understanding at least! You can always layer serums/ampoules, especially if they have different effects, but it's also possible to overwhelm your skin with products, so balance is definitely key!

so I think they’re used interchangeably but from what I’ve noticed, serums tend to me thinner and more lightweight and ampoules are thicker. they both do the same thing in the end, just different formulas.

I only use one of them. They're very similar on my opinion.