iCloud Drive different across two MacBook Pro

When a new Mac is purchased you have to set it up manually see this https://support.apple.com/en-us/HT205749

And turn on iCloud Drive https://support.apple.com/en-in/HT204025

Note : I cloud drive won't set up by its own , you have to sign in with Apple ID and password in new Mac , the steps are performed by an administrator and works for an individual device , its your choice to use the same Apple ID and password in old Mac and add desktops and documents https://support.apple.com/en-us/HT206985

In old Mac if iCloud Drive was turned on , the desktops and documents were checked and the iCloud storage space was in limits .

Once you sign in with same Apple ID and password on new Mac , if the device are on the same network ( here in the new Mac iCloud Drive is turned on , desktops and documents box as checked ) .

The iCloud data it could be your files , personal documents created with Microsoft office or others will start syncing but it can take few hours ( high network speed is essential ) both Macs with files / documents will sync and the iCloud data will be equalised read these https://support.apple.com/en-in/HT203052

https://support.apple.com/en-in/guide/mac-help/mchlp1774/10.14/mac/10.14

There are different method of file sharing https://support.apple.com/en-us/HT204350

https://support.apple.com/en-in/guide/mac-help/mchlp1122/10.14/mac/10.14

Ineligible files or file size greater than 50 gb will not sync , third party apps like documents created with Microsoft office , word , file will not sync .

Is the same version of MacOS X running on both machines?