VFC UMP9 vs UMP45

Greetings!

For VFC UMP users.

Wondering about the VFC UMPs, I’ve seen that VFC released an “upgraded version of UMP45 in 2018, and a year before that, there was UMP9, that was already considered better than UMP45 before the UMP9.

Is there actually any difference between the UMP9 and upgraded version of UMP45 in terms of internals particularly?

Thanks for any info!