Your elementary school Math teacher likely once told you that every square is also a rectangle. You may or may not have believed them, but technically they were right.
Well, guess what? Every decal is technically a sticker! They have nearly the same vinyl material choices, and cut options: die-cut decal, die-cut stickers, too.
Decals are a form of a sticker. Like pinot noir is a form of wine. In this analogy, stickers are the wine in general and decals are just a specific type of vino. (Oh, we also print wine labels).
Just like squares, rectangles and wine, the biggest difference between stickers and decals is their distinctive reputations.