These machines are very similar. Both have digital displays, automatic egg turning, automatic humidity control and hold the same amount of eggs. The difference is that Pro version has been designed for breeding falcons or exotic birds that can be more difficult to hatch and often require very specific settings.
The Rcom 20 Max has a temperature display, humidity display and indication lights for water level, egg turning and heating. You simply set the temperature and humidity levels to match your requirements. The Rcom 20 Pro has a much more specialised program which includes a species selector from which you can select your desired species and the machine will automatically adjust to the recommended settings for that species. The Pro will also count down the days, turn off the egg turning 3 days before hatch and increase the humidity on your selected day.
The main attraction of the Pro is that it offers much more tailored turning options. You can set the machine to turn the eggs from 45° up to 180° at 15° intervals (based on a typical hen-egg size). There is also more flexibility on when the eggs turn; it can be set to turn every 20 minutes to every 3 hours. Whereas, on the Max version, the turning is only able to turn 180° at 1-, 2- or 3-hour intervals.