M35FA-03-STD vs M35RMB-04-STD


I would like to ask about the differences in GSM modules M35FA-03-STD vs M35RMB-04-STD.
I ask because since the introduction of the module (GPS locators) M35RMB-04-STD, we have a problem with delaying data transmission.
Sometimes the device has a problem with proper communication, as if it had a problem with entering the network.

Are the changes in this module serious enough to require, for example, a change in the software of the device? Can he work in the EU?

Greetings, Jakub.

These two are very different, they use different chip manufacturers.