What is the difference between the John Deere 6R 130 and 6M 130?

Here is how the John Deere 6R 130 and John Deere 6M 130 compare on John Deere's published specifications:

• Horsepower: John Deere 6R 130 128 hp vs John Deere 6M 130 129 hp
• Pto horsepower: John Deere 6R 130 101 hp vs John Deere 6M 130 100 hp
• Weight: John Deere 6R 130 14330 lb. vs John Deere 6M 130 13889 lb.
• Fuel capacity: John Deere 6R 130 52.6 gal. vs John Deere 6M 130 54.2 gal.
• Wheelbase: John Deere 6R 130 102 in. vs John Deere 6M 130 102 in.