Some CL850īs are refurbished CRJ200īs (I guess any CL850 delivered since Bombardier closed the CRJ200 production line a while ago in order to build 900's and now the 1000īs) ,
AFAIK itīs the same aircraft, just different interiors and seats, and I have read somewhere that it has an extra fuel tank in the back where the toilet is in the CRJ200, but is basically the same aircraft (systems and engines and all that).
I read they put new/overhauled engines also when transforming them into CL850's.
No need for differences training for pilots, should be the same for engineers.
LEVC