What is the difference between the John Deere 612R and 600R?

Here is how the John Deere 612R and John Deere 600R compare on John Deere's published specifications:

• Horsepower: John Deere 612R 355 hp vs John Deere 600R 375 hp
• Wheelbase: John Deere 612R 169.3 in. vs John Deere 600R 169.3 in.