The Yh willfill faster, but generates a lot of heat. It requires an external water supply for cooling and uses an oil ba=th for lubrication. The CS4 is lubed by grease so no oil is needed. It runs significantly slower so it won't fill as fast, but will run significantly slower. If you are just filling guns, and you don't need them filled in less than a minute or 2, then the CS3 might be the better choice. If you want to fill tanks, then the YH might be a better choice, or go with the CS4. I've had 2 YH compressors, neither one lasted more than a year before they failed, and trying to rebuild them was not successful. The CS3 I had never gave me any problems. I've only had the CS4 for about 2 months, so to early to report on longevity, but so far, it's been the best compressor I've owned.