I'm curious about the difference between ampoules, serums, and essences.

While looking for basic skincare products, I often came across products called ampoules, serums, and essences.
At first, I thought it was a similar product with just a different name.
However, looking at the descriptions, there was a lot of talk that ampoules, serums, and essences each have different roles.
So I am wondering if it is right to use all three.
I am also wondering if using just one is sufficient.
Some articles state that ampoules have the highest concentration, while others explain that essence is the basic step.
They say serum is an intermediate step, but I'm not sure if there is actually a difference in real-world use.
I am confused whether applying the ampoule, serum, and essence together leads to better skin care or if I am just using products with similar functions.
I am worried that this might just be increasing the steps for no reason.
I would like to know what criteria I should use to select ampoules, serums, and essences when choosing basic skincare products.