As far as I understand, GREAT is a really a template for LEAP intended for use at the city scale in China. In other words, it is a suggested data structure plus various default data. GREAT is developed by staff at the
China Energy Group at the Lawrence Berkeley Laboratory in California, whereas LEAP is developed and managed by the Stockholm Environment Institute. GREAT is distributed as a ".leap" data file that can be installed into LEAP by double-clicking the data file. However, it is not currently distributed as part of LEAP.
I believe you can download GREAT directly from that page, but if you have any questions or concerns I suggest you email LBL staff. Nan Zhou is the Director of the China Energy Group LBL. Her email is nzhou@lbl.gov