ZENOLOGY GX for iPad uses the exact same Roland ZEN-Core Synthesis System found in ZENOLOGY Pro and Roland hardware products such as the FANTOM, JUPITER-X, JUNO-X, RD-88, MC-101, and MC-707.
The only difference between ZENOLOGY GX and ZENOLOGY PRO is the support for Model Expansions. ZENOLOGY GX does not support Model Expansions at this time.