What are the changes over the previous version? Thanks

If you are talking about differences between the 'October' release and the newly posted 'December' release of Primo 2:

None.
No operational or feature changes whatsoever.
If you already have a fully working 'October' release, there is no reason to make any changes to it.
The newer EXE is just newer....that's all.

The december build is nothing special. It is an official build for the Russian market only (and for a particular device - as are more recent builds).