Really there is none. Mabie if you need to carry more paint,
I love this pack! it is the most comfortable pack I have ever used. There is two layers of padding behind the pods and the thinner belt is so easy to move in. The pods are held snuggly in place with no bonce at all but are easy to get out when needed. The cover that goes over the pods is also padded and designed to deflect balls so you can stay in the game longer. The tight profile makes playing the snake and tight bunkers a breeze. You get all this at an ubalivable $35.00 with free shipping and its all made in the usa.
If your looking for a speed pack type of pack, this is the one you need. More comfortable, better fitting, better looking than other speed packs.