Functions of Xbee Pro

I have 2 xbee pro 63mW and i configured them like this : one is a Zigbee Coordinator AT , the other is a Zigbee Router AT . They work very well , but i want to know details of each functions and which one choose for my xbees (maximum range 3.2 km ) !
This is the posibilities :

END DEVICE - LTH
ZIGBEE COORDINATOR API
ZIGBEE COORDINATOR AT
ZIGBEE END DEVICE API
ZIGBEE END DEVICE AT
ZIGBEE ROUTER API
ZIGBEE ROUTER AT
ZIGBEE ROUTER/END DEVICE ANALOG IO
ZIGBEE ROUTER/END DEVICE DIGITAL IO

Help me please XD

Go to digi.com and download the product manual for the particular XBee you have, it will explain everything.

ok thx