There is usually always a international version of a device as well as a US version.
The US has a different version due to our regulations on radio wavelengths and such. The Federal Communications Commission requires this.
Updates for devices, like the multi window update for the note 2, are controlled by the carriers. With all of their testing and software that they need to add to the updates, sometimes the updates can lag for quite some time. Also, depending on bugs that may pop up in the updates from the manufacturer, that could also delay updates from the carrier.
When it comes to Samsung, no one is really due why their Wi-Fi only devices take forever to get updates. I have a note 10 tablet and it still hasn't seen the multi window update yet either. It has been out longer than the note 2 also.
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