Those CAN be two different things. A two cylinder is just that. It has two cylinders to pump even more air. Some look kinda like a V-twin bike engine. Some are inline two cylinders. But they don't HAVE to be a two STAGE if they are two cylinder. Two stage compressors come in most every cylinder configuration there is. In a nutshell, basically, it's like having two compressors in the same compressor housing. A big one and a small. The big one compresses the air, sends it to the small one that in turn compresses it more and then to the tank. Two stage units are best for heavy duty use like shop air where continuous use is high. Like a body shop running DA sanders and spray guns. They are more expensive than a single stage but support more work. They pump up at a much faster rate and "keep up" with work better.
