What is the difference between the John Deere CS770 and S7 900?

Here is how the John Deere CS770 and John Deere S7 900 compare on John Deere's published specifications:

• Horsepower: John Deere CS770 515 hp vs John Deere S7 900 543 hp
• Fuel capacity: John Deere CS770 270 gal. vs John Deere S7 900 330 gal.