The primary difference is that the Auto Mate type wall mounted dispensers can run on batteries or transformed AC power, where the Auto Pail Top is battery operation only. While it doesn’t take much power to keep the memory working, it does take significant power to run the pump, so there will be battery changing required. If the customer is providing batteries, at some point they will forget to change worn batteries, causing failure to pump and potentially driving the drain maintenance program out of whack. If the salesperson is changing the batteries, it’s a sure bet that the customer will call you about the pump not running at the most inconvenient time possible (Murphy’s Law). When using the Auto Mate type, as long as there is an AC outlet close, you will not need to use batteries and all the downsides of them will disappear. I would always choose to use a wall mounted dispenser if AC outlets are available for reasons of reliability and stronger pump action. By the way, the Auto Mate type wall mount dispensers can also be run on batteries (8x 1.5V D-cell) if no AC power is available.