Hello,
1) RUT955 can be considered as an expanded edition of RUT950. It is the same device with some additional features, specifically, GPS capabilities, USB 2.0 port, Micro SD slot, RS232/485 serial communication ports, more inputs/outputs.
2) Both devices are manufactured with the same modem modules, thus, in regards to mobile connectivity, there is no difference between the routers.
3) The difference between device versions primarily is in the modem module. Global version has support of a wide range of frequency bands as well as older radio access technologies: 3G and 2G.
Best regards,