What is the difference between the John Deere 9RX 540 SCRAPER and 9R 590?

Here is how the John Deere 9RX 540 SCRAPER and John Deere 9R 590 compare on John Deere's published specifications:

• Horsepower: John Deere 9RX 540 SCRAPER 533 hp vs John Deere 9R 590 582 hp
• Weight: John Deere 9RX 540 SCRAPER 56714 lb. vs John Deere 9R 590 45122 lb.
• Fuel capacity: John Deere 9RX 540 SCRAPER 400 gal. vs John Deere 9R 590 400 gal.
• Wheelbase: John Deere 9RX 540 SCRAPER 162.5 in. vs John Deere 9R 590 154 in.