The inside of the light dome of the RAIN2 (tm) looks simple. What you can't see is the wiring inside the waterproof submersible white case of the GEM5® lights which controls the heat of the LEDs so that it does not have to reduce power when out of the water (like apparently all other submersible light have to do).
The two independent growth compartments of the SURF8 and 8x (lights not shown) allow you to clean/harvest one while letting the other continue to grow/filter. This reduces the nutrients yo-yo effect that can occur after cleaning a regular one-compartment or one-screen scrubber.