The most simplistic way to break down the difference between a sealer and a waterproofer is where the product settles. Sealers provide a protective layer on top of the concrete. It prevents anything from reaching the concrete in the first place, which is a great way to protect against stains on the concrete itself. Meanwhile, a waterproofer penetrates into the concrete itself to fill gaps and other porous areas. This helps protect the concrete since the elements can’t work their way into it. However, it doesn’t sit on the top. There are advantages and disadvantages to both waterproofers and sealers.