Firmware support for XBee-PRO XSC modules can vary according to the hardware revision letter shown on each module.
XBee modules with revision G and earlier only support "XBee-PRO XSC (S3B)" firmware. However, modules with revision H and later can additionally support "XBee Pro 900HP 200k" (DigiMesh) & "XBee Pro 900HP 10k" firmware apart from original "XBee-PRO XSC (S3B)" firmware.
This difference has occurred due to lack of memory space available in earlier revisions of this hardware which wasn't sufficient to store two newer released firmware of 900HP modules.
Sep 20, 2017