The main difference is that the FROG may be used for soil, water or air sampling. The VOCAM may only be used for air sampling, and is primarily for distributed, fixed, or perimeter monitoring. The VOCAM has a heated PID to keep the PID lamp cleaner for longer periods of time. In addition, VOCAM has a regenerable hydrocarbon scrubber. System integrators will find the VOCAM to be a very compact robust solution for distributed sensing applications.