Here are just a few things I found lacking in the iPadOS version compared to the desktop client
Cannot pin tabs, at least not via right click menu on tab. But then low power mode says that pinned tabs won’t be unloaded. Low power mode is also rather aggressive about unloading even prior to 30 minutes
No menu bar support whatsoever, accessing anything on the farthest right … menu requires so many more presses, is not easily accessible. Using the menu bar to do Orion > Orion Settings… takes you to the iOS settings app instead of the ‘actual’ settings
The menu on the left of the URL bar sometimes force closes itself, making it impossible to use
The find/CMD F overlay cannot be exited with the same shortcut
Multi-window support like Safari
I’m sure there are many more things more longtime users or Orion developers can add to here, can just copy iPadOS Safari