Difference between E200 and E250 is the level of trims and engine power output.
Engine capacity wise, both E200 and E250 uses the same engine, for W212 pre-facelift both uses 1.8T M271 DE18 engine, facelift version uses 2.0T M274 DE20 engine, but the power output are tuned differently. Needless to say, E250 has higher power output than E200, can accelerate faster, have higher top speed.
E200: 135 kW/270 N⋅m
E250: 150 kW/350 N⋅m
Trim wise, E250 have more stuff like sunroof, larger diameter rims, etc.
Depends on your budget, E200 is cheaper than E250. Again, you get what you paid. If you are just looking for a comfortable ride, E200 is enough. If you are looking for more omph and more gadgets, E250.
Traditionally, Elegance trim (E200) is comfortable than Sports trim (E250).
I have to reiterate this again, can you comfortably afford a brand new E200/E250? If no, stay away from their second hands. You most probably have difficulty maintaining one later. Servicing at SC, RM8XX for a basic maintenance service. If not mistaken, RM6k for all discs and pads. RM3k for each absorber. If you service outside without any trusted mechanics, you ended up get butchered since you are driving a luxury car. You may save some from labor charges, but those spare parts cost about the same. So if you can comfortably afford a RM370k car, you can afford RM10k-30k service bill and keep your car running. Else you will become like those youngster driving 2nd hand Mercedes/BMW but no money to keep the car in running condition, ended up stalling beside the road.
For TS, this your answer.
Add on: From what I know if it's AMG spec, SC charged more than 10k for all disc, pads and brake fluid.
Different between servicing in SC and reputable workshop is about half the price.