I just purchased a Z9X Pro and upgraded to the latest firmware version 1.0.65G which contains the Google Play Store. I was able to install Kodi 20.2 from the play store and it seems to be working as expected. My question is: Is this the same as ZDMC? If not, what's different and should I use ZDMC instead. Thank you
No. ZDMC is a fork that uses the internal Zidoo player for most content, so that you get the best of both worlds.
Auto Refresh Rate in Kodi will not work on the zidoo (and you can only select 1080p max in the Kodi settings), and you cannont select Zidoo as an external player, hence most people use ZDMC.