Countertop soft serve ice cream machines are the smaller of these two types, and (as the name suggests) can be placed on top of the counter. They are most practical in shops or restaurants that have limited floor space, and are perfect as an addition to already established shops. Because they are smaller, these models can either be a low volume machine or a medium volume machine, and are thus recommended for shops where the demand for soft serve ice cream is not that high.
As opposed to the above, floor model soft serve ice cream machines are placed on floors (much like a refrigerator like the Sanden SPU-1253 upright (display) fridge) and have rollers on them for easy maneuvering and transport. These are of course bigger than countertop models, and also has bigger volume (they are usually medium to high volume machines) and capacity. Because they are bigger, they are able to dispense more soft serve ice cream and are thus recommended for shops that have high demands for the product.