They are very similar but not identical.
 Xiaomi Mi Robot Vacuum Cleaner 2 ULTRA (
https://www.mi.com/global...):
Powerful 4000Pa suction
3D obstacle avoidance technology
New LDS laser navigation
High capacity 5,200 mAh battery.
Cleans up to 240㎡ per charge 
Xiaomi Mi Robot Vacuum Cleaner 2 PRO (
https://www.mi.com/global...):
Multi-stage mapping, slot memory.
Battery: 5200 mAh
Suction power 3000Pa
3 suction modes
Supports OTA updates 
More information here: 
https://www.mi.com/global...