I have been trying to find the difference between these two XBee’s, though I haven’t found a concise list of differences. Can anyone help me out. Thanks.
Whoa! There is very little the same 
The pins I guess.
S2B is a Zigbee, 2.4Ghz, so does routing, wants you to send unicasts using 8-byte MAc addresses, has a complex ‘socket-like’ structure with end-points, profiles and so on.
XSC is 900Mhz, a rather older idea assuming you broadcast to 16-bit node ids. Has little other structure. It is a more traditional radio, but does support that ‘filtering’ so the XSC will (much like an Ethernet MAC) discard packets not addressed to it.
Although they are hardware compatible, code written for one will likely require heavy modification to use the other.
If you want both a 2.4 and 900 long-range solution, you are better to pair these:
S1 (802.15.4) & XSC
- or -
S2B (ZigBee) and the DM09 (DigiMesh 900Mhz)