XBEE S2 can communicate with only S2
Features:
3.3V @ 40mA
Same pin out as XBee Series 1.
250kbps Max data rate
Default UART interface: 9600, 8-N-1
2mW output (+3dBm)
400ft (120m) range
Built-in antenna
Fully FCC certified
6 x 10-bit ADC input pins
8 x digital IO pins
128-bit encryption
Local or over-air configuration
AT or API command set