NT and NTU

Can someone clarify this for me please?
I have an old nuvi 205 (without the "W"), that has only gmaptz and gmapbmap installed in the internal memory.
So I wanted to update the device with the latest map - so with the Europe NT 2025.10 (the latest NT maps for Europe).
The thing is, that I've accidentally copied the file "South (D6210320A).rar - 2.4 GB" from Europe 2026.20 NTU onto the sdcard.
There is 100% no other maps on my device, because if I eject the sdcard, it says "there is no detailed maps ..."!
But now I can enter the address and the nuvi makes me a normal route ... :o
So whats the catch? I thought NTU map shouldnt work at all if a garmin only supports NT maps :o
Or will I notice some other problems during usage?

"U" means "Unicode. I suppose there may be problems witn non-Latin symbols. Or maybe the Garmin accidentially make non-Unicode map instead of Unicode.

ruski76 wrote:So whats the catch? I thought NTU map shouldnt work at all if a garmin only supports NT maps :o
Or will I notice some other problems during usage?

Your device was not designed to use NTU maps. Some members have reported using NTU maps successfully on older devices already, but if you get errors you will know what it is.
Automotive devices that where designed to support both NT & NTU can easily be identified by searching the garmindevice.xml for "Unicode"