@bobbles gave you the main answer.
Z wave operates on different frequencies in different regions. The frequency of a device like an electrical outlet must exactly match the frequency of the hub or they won’t be able to talk to each other . These frequencies are set at the time of manufacture and cannot be changed afterwards. In some areas, the frequency requirement is set by law. In others it’s just custom.
UAE uses the same zwave frequency as Europe and the UK. So Z wave devices certified for use in the EU should work with the UK model of the SmartThings hub, and most zwave devices that you might buy locally in UAE would be on this same frequency. (I don’t know if the law in UAE prohibits the use of the US frequency there or not.)
The most precise way to tell the difference between devices intended for the two regions is to check the radio frequency.
The EU/UAE frequency is 868.4
The US/Mexico frequency is 908.42
Some companies such as Aeon Labs manufacture the same devices on different frequencies for sale in different regions, so always check the exact frequency of the device that you are purchasing.
The Z wave alliance keeps an official site with a list of certified devices for each region:
If you want to make things as simple as possible, you can just select devices from the official “works with smartthings” list for the UK.