Don't know about CX but for the EK a/c
The 220's have RR 877 at 77000 lbs. MTOW 242 t
The 200er's have RR 892 at 92000 lbs. MTOW 286 t
The 300's also have RR 892 at (yes , you guessed it) 92000 lbs MTOW 299 t
The 200er's and the 300's have the same fuel load, so the 300 has less range because of it's heavier wt. The 200'er's have the best power to wt ratio, the 300's the worst
The 300 er's have GE 115's at 115000 lbs
The 200 LR's will have GE 110's at 110000 lbs Exactly the same engine, in fact they are interchangable, it's just a data card change