The break tank option on warewashing machines is a mechanism employed to prevent water from within the equipment flowing back in to the water supply. This prevents any contamination and is vital to establishments such as care homes or catering businesses.
A drain pump is used in circumstances where waste water from the machine needs to be pumped in an upwards direction in order to flow to the drain.
You can read more about these two warewashing features here: https://www.247cateringsupplies.co.uk/thekitchenthink/buying-guide-commercial-ware-washing/