What's the difference between active and passive balance in battery management system ?

Balancing can be:

Passive balance,so-called charging balance, it happens during charging when one lithium cell in a battery pack first reaches the certain voltage,balance voltage. The resistor will start dissipating energy of this cell, slow down its charging and let other cells catch up with it. Passive balance current is normally between 35mA to 80mA

Active balance, rather than dissipating energy of the high voltage cell, it transfers energy from high voltage cell to its neighbor low voltage cell. It happens during charging, discharging and sleeping mode. As long as the voltage difference between two neighbor cells reaches setting value, say 1V, it starts functioning. Active balance current could be 1000mA to 5000mA.

In brief, passive balance works by dissipating energy of the high voltage cell while active balance transferring energy from high voltage cell to low voltage cell next to it. Passive balance is charging balance while Active balance has nothing to do with battery's working status