Well Grasshopper,
Just so you know, expect to pay two grand and up for a true industrial duty compressor. You don't need that quality unless you intend to open up your own sandblasting shop and run that compressor 8 hrs a day, every day.
The gas powered compressor is a two-stage unit that is capable of storing air at 175 PSI. A 2-stage sucks air into a large diameter cylinder, compresses it and then passes it to a small diameter 2nd cylinder that compresses it even further in order to get to 175 PSI.
The two electric compressors are both single stage but they use three cylinders feeding into a common line that is connected to the tank (receiver). Each cylinder comes up on the compression stroke every 120 degrees of rotation. Single stage compressors do not compress the air to a point higher than 140 PSI.
If this was just supposed to be a home shop compressor capable of running some air tools such as impact wrenches and air ratchets etc, then the $700.00 unit would be my choice. However, you want to run a pressure pot sandblaster and so you have to look at the number of CFM's as well as the pressure those CFM's are delivered at. The $1000.00 unit would be my choice for that application due to the bigger pump. It seems a bit weird that this one has the 60 gallon tank and the other one has the 80, but that wouldn't influence me because it's not about the size of the tank.... it's about the size of the pump.
Pressure pots have a ceramic nozzle on the end of the hose. Different size orifices are available. Smaller orifices use fewer CFM. All orifices increase in size as you use them. What you want to happen is for the compressor to run steady and constantly deliver 90 PSI of air to the pressure pot at whatever CFM the nozzle needs. Having the compressor start and stop, start and stop, start and stop is pointless. That just shortens the life of the starter switch.