What is a backpack?
A backpack is a type of bag that has straps for carrying it. The straps generally sit on the shoulders but varieties can also include straps that cross the body. Backpacks have traditionally been used for carrying larger loads than usual bags, especially in long walking trips.
WHAT ARE CROSS-BODY BAGS?
A cross-body purse style is made with one long strap that crosses over the body with the bag section resting at the front by the waist. The design of cross-body bags made them ideal to be used in the transportation of mail and other goods delivered by different types of messengers.
Anyway, the right choice for you depends on several factors including style, features, and how the bag will be used. Weigh the pros and cons to decide the right choice for you.