What are the differences between indoor, outdoor, and indoor/outdoor
Made of full-grain leather
Requires being broken-in for optimal use
Feels smooth and has superior grip
Reliable/consistent bounce characteristics
Expensive - due to cost of materials
Made of rubber or synthetic leather
Can be used right out of the box
Feels rough and has less than superior grip
Does not have as reliable/consistent bounce characteristics
Not as expensive
Is it a design/material difference?
Yes. Full-grain leather vs. rubber/synthetic leather.
Is there a need for the difference [between "indoor" and "all-surface" basketballs]?
Yes. Basketballs are made specifically indoor use or all-surface (outdoor, indoor/outdoor) use. (1) (2)
Indoor basketballs, when exposed to outdoor elements such as asphalt, dirt, and moisture, wear out sooner than all-surface basketballs.
Using indoor basketballs indoors and all-surface basketballs indoors or outdoors will maximize the life of each type of basketball. The cost to replace an indoor basketball is more than the cost to replace an all-surface basketball.