Cube firmware

I have read the solo cube posts and the cube black firmware posts. Still I am not sure of the best option. I bought two used solo cubes. I also have a cube black. So far the only firmware that seems to run without errors is the PX4 version. Is there physical differences between the 3DR cube and the cube black? What is the best firmware version for either?
TIA

https://docs.cubepilot.org/user-guides/autopilot/the-cube-module-overview

Scroll way down to Cube Module Overview and it shows the differences between cubes. It appears that the green cube uses different voltage?

Thanks, I have reviewed all this, but when using the cube black firmware I get sensor errors and failed to recognize messages. With the solo cube firmware I get battery sensor errors that won’t go away. Only the PX4 firmware runs without errors. Also if I install ardu firmware from QGC I get a whole different fmu-v2 or v3 firmware.

It appears that they only have firmware for Cube green for copter.

So maybe this answers some of this question. Finally found a retailer selling the solo cube 2.0 posting the hardware specs and they are different from the cube black posted from hex. Posting a screenshot if allowed.