maple
maple bats are extremely hard an dense and therefore aid the ball in jumping off the bat faster then any other type of wood.
the surface itself is approximately 20% harder and has closer grain than ash. the hardness of maple makes it the least flexible

ash

ash is much more flexible than maple and has a "trampoline" effect when it strikes the ball. instead of jumping off the bat like maple, ash bats have a springboard effect and absorb contact withe the ball. ash bats usually have a bigger sweet spot which gives them a bigger area to make solid contact.