What is the difference between the John Deere 6R 230 and 6M 240?

Here is how the John Deere 6R 230 and John Deere 6M 240 compare on John Deere's published specifications:

• Horsepower: John Deere 6R 230 227 hp vs John Deere 6M 240 237 hp
• Pto horsepower: John Deere 6R 230 184 hp vs John Deere 6M 240 194 hp
• Weight: John Deere 6R 230 21716 lb. vs John Deere 6M 240 19180 lb.
• Fuel capacity: John Deere 6R 230 107 gal. vs John Deere 6M 240 85.9 gal.
• Wheelbase: John Deere 6R 230 114 in. vs John Deere 6M 240 110.2 in.