What is the difference between the various models of 3M respirators (Versaflo series)? How strong is the protection?

As far as I know, 3M Versaflo series respirators mainly have TR-300+, TR-600, TR-800, etc. All three are electrically powered air-filtering respirators, and the strength of the protection is increased in turn. TR-300+ is mainly for particulate protection, and TR-600 can protect against particles, gases, and vapors.