The difference between calzone and stromboli is straightforward. You can tell them apart in these three ways:
Fold - Calzones are folded in half to seal them, while stromboli is rolled.
Cheese - Calzones traditionally use ricotta cheese (or a mixture of ricotta and other cheeses). Stromboli usually uses mozzarella cheese, parmesan, or even cheddar.
Tomato sauce - Calzones use marinara sauce for dipping instead of inside the hot pockets themselves. Stromboli rolls the sauce in with fillings.