What is the difference between the John Deere 600R and 616R?

Here is how the John Deere 600R and John Deere 616R compare on John Deere's published specifications:

• Horsepower: John Deere 600R 375 hp vs John Deere 616R 375 hp
• Fuel capacity: John Deere 600R 149.2 gal. vs John Deere 616R 149.2 gal.
• Wheelbase: John Deere 600R 169.3 in. vs John Deere 616R 169.3 in.