BTEG CKD4B 004Arshaant station Arshaant station

In Mongolia:
UBTZ - Ulaanbaatar railway
MTZ - Mongolian railway
BTEG-RW - Bold tumur eroo gol railway
ERRW - Energy resourse railway

What is the difference between UBTZ and MTZ? It is written everywhere, that UBTZ and MTZ is the same company, named in different ways.

http://www.mtz.mn
http://www.ubtz.mn/
http://www.legendtour.ru/rus/mongolia/informations/mongolia-tra..shtml
http://mongol.su/wiki/index.php?title=%D0%A3%D0%BB%D0%B0%D0%BD-..D0%B0

http://trainpix.org/vehicle/38238/#n6174 says that it owned by UBTZ

@Batkhurel

Maybe MTZ maintaining all infrastructure while UBTZ owning rolling stocks and passenger/freight operations?

@Mikhail

This one is really owned not by UBTZ, but by BTEG and is used on its private line.

UBTZ- Mongolian and Russian joint stock company.
MTZ- Mongolian railway company. (new since 2009)