What is the difference between the John Deere R4023 and 408R?

Here is how the John Deere R4023 and John Deere 408R compare on John Deere's published specifications:

• Horsepower: John Deere R4023 173 hp vs John Deere 408R 280 hp
• Wheelbase: John Deere R4023 147 in. vs John Deere 408R 169.3 in.