The CRJ's Rockwell Collins FMS-4200 as used in the CRJs is a 1980s design and is far "cruder" than the G1000. You have a little control head with a small display screen and keyboard where you interface with it. The G1000 is more like using any modern computer application where much is presented on the main screen with trackball or mouse selectable commands and data with a fairly intuitive presentation. On the FMS-4200, you have keys on the side of the display to select options that appear next to each key, keys to select various modes on the control head, and you have a one-line "scratchpad" where you can type in text commands or other data.
You could say it's a bit like the difference between using the icon based Windows operating system and the older direct key entry MS DOS. With a system like the 4200 you have to learn the selections and menus and keystrokes directly, instead of just knowing how to find your way around a pictorial presentation on a large screen that you use like any modern computer application.
If you've mastered the G1000 and you later find yourself on a CRJ type course having to figure out its 1980s FMS system, your G1000 skills probably won't help you that much and you'll just have to figure out the "old school" interface as something new. To get though the type course in one piece, mastery of the FMS is critical, so if the opportunity to go on that course comes along, get hold of the training material as early as you can to get as much of a head start as possible.