What are the main differences between the HP LaserJet Professional P1560 and P1600 printer series?

The P1560 series prints at 22 A4 ppm or 23 letter-size ppm and supports manual duplexing only, while the P1600 series prints faster at 25 A4 ppm or 26 letter-size ppm and supports automatic duplexing. The P1600 also includes on-board networking capability in addition to USB connectivity, whereas the P1560 only has USB. Both models have the same tray and output bin capacities (10-sheet priority slot, 250-sheet main tray, and 125-sheet output bin).