Hours mode splits the pool by hours worked. Points mode uses the points you assign. Role mode multiplies hours by a role weight, so two people with the same hours and weights of 1 and 2 receive one third and two thirds. Leftover cents go to the largest remainder so the shares add up to the pool.
A $100 pool and hours of 6 and 4 is $60 and $40. The same pool with points of 1 and 3 is $25 and $75. The calculator stays free.