What is the difference between Siemens programming cable USB-PPI and RS232-PPI?

The interfaces of Siemens programming cables with usb-ppi and rs232-ppi are different.
Extension: Siemens programming cable for connecting Siemens PLC to computer, available in various models.

Type:

PC/TTY corresponds to Siemens product number :6ES5 734-1bd20,RS232 to Siemens S5 series PLC programming port (DB15) communication interface cable, 3m. RS232/ current loop interface for S5 series PLC programming software and monitoring system.

USB/PPIUSB interface Siemens s7-200 PLC programming cable, USB/PPI interface, 3 meters, with communication indicator light, corresponding to Siemens product number: 6ES7 901-3db30-0xa0, the maximum communication distance up to 2 kilometers.

USB/PPI+ isolation USB interface Siemens s7-200 PLC programming cable, USB/PPI isolation, 3 meters, with communication indicator light, corresponding to Siemens product number: 6ES7 901-3db30-0xa0, the maximum communication distance up to 2 kilometers.