tinknocker1989

Hi every one, have a stupid question about the 20v line. I recently bought the 20v drill & impact combo that came with 2 1.5ah battery's. Planning on picking up the reciprocating saw and noticed it comes with the 3.0ah battery. Are certain tools in the 20v line designed to use one or the other battery (1.5 vs 3.0)? Will interchanging the batteries cause damage to the tool out battery's? Or does it just come down to run time? Thanks