Both crisps and crumbles have a baked fruit base, so the difference lies in the topping. Crisps tend to incorporate oats and/or nuts into the top layer. On the other hand, crumble toppings are typically just made up of flour, butter, and sugar—leading to a "crumbly" cakey texture as opposed to a "crispy" toasted texture. However, I will say that the crisp v. crumble debate might also be a regional one. A few of my east coast buddies call every baked fruit dessert a cobbler, which infuriates me and delights them.