The base system of both controllers comes with one temperature probe and one pH probe for out-of-the-box monitoring. It also comes with 8 ports that you can use to control your equipment. In addition to that, it comes with 2 float switches for you to implement your own Auto Top Off and forget about manually adding water to your tank.
The preloaded code is factory configured to control ATO, Moonlights, Daylights, Actinic Lights, Wavemakers, Heater and Return Pump. It is also configured to dim your LED lights for a sunrise/sunset effect throughout the day.
The only major significant difference between the two models is the memory size.
With the Reef Angel Controller, you will be able to monitor and control everything in the table above, but you will be limited on how much custom code you will be able to fit and also on the number of expansion modules you will be able to expand in the future.
On the other hand, with the Reef Angel Plus Controller, you can do all the above and still have memory space for all current and future expansion modules.