They have a pretty similar taste because they’re both primarily made out of sugar, but caramel is softer because it’s pure sugar while toffee is made with sugar, butter, and flour. The flour is what gives toffee a crunchier texture. In this recipe we use both caramel and toffee because they’re used for different things - the caramel gives the apples the classic gooey caramel apple flavor, while the toffee balances out the soft and gooey textures with some crunch.