Hi Francesco
The Duet Ethernet is not equivalent to the 0.8.5. The key differences are the Ethernet has a more capable processor and the TMC2660 stepper drivers.
A feature list for the Ethernet is available here:
https://duet3d.com/wiki/Duet_Features
Also see the hardware overview:
https://duet3d.com/wiki/Hardware_overview
The 0.8.5 is near the end of its product life.