What is the difference between the John Deere 616R and STS16?

Here is how the John Deere 616R and John Deere STS16 compare on John Deere's published specifications:

• Horsepower: John Deere 616R 375 hp vs John Deere STS16 400 hp
• Fuel capacity: John Deere 616R 149.2 gal. vs John Deere STS16 135 gal.
• Wheelbase: John Deere 616R 169.3 in. vs John Deere STS16 180 in.