There shouldn't be, provided you get one from a Jap model with the equivalent drive train. (You should find that your UK models were actually fully imported from Japan - check the manufacturer plates in the engine bay.)
David, I'm not certain what experience you have with the "Japanese" models, and I am assuming here that by "Japanese" he means used JDM (Japanese domestic market) rather than a Japanese export - BUT - in my experience, the only way to know is to examine the vehicles.
You would think there should be no difference, assuming equivalent drive trains, unfortunately that is not always the case - as an example - in the export markets the pneumatic freewheel front differential used on the 98~05 GVs was only fitted to SQ series vehicles, but, I have a spare pump that I took off of a JDM SE series Escudo (year unknown - I found it on a front cut whilst looking for something else.
Strictly speaking this is a case of a Vitara front differential being different to it's equivalent Escudo front differential, but, if it happens on a Vitara, it can just as easily happen on a Grand Vitara.
I've also seen this on other marques - I have a used JDM Mitsubishi Pajero iO - Australian market vehicles shipped with a torsen style limited slip diff in the rear of the 5 doors, but mine has an open rear diff.
He did ask differential (axle) so it could be either - to use my example, the SE Escudo, the axles are also different - the actual diff hemisphere is reduced in size and offset within the center to make space for the freewheel clutch assembly - this requires longer splined sections.
And yes, I do have access to the parts system, unfortunately, it's export market only - I can see pretty much every Suzuki built for export, but nothing built for domestic use.