No, they are not. Gx64 (GR64/GS64) have the same form factor as Q64. GRSoft app in GR library implements most of the AT commands present on GR64/GS64. The similarities end there. Firmware architecture, Firmware releases, baseband, bootloader, TCP/IP stack, etc are completely different.
Some inputs on your other posts in the forum about Gx64:
WMSN is present in Q64. It is not present on Gx64. It isn’t listed in Gx64 AT manual.
M2MPower IDE is a Gx64 specific IDE. It is not related to M2MStudio. There is no Open AT on Gx64. It had a different set of C based APIs.
R65c Firmware is compatible with Q64 and not with Gx64. If I remember correctly, 4-5 years ago, R5A was released as the final maintenance firmware for Gx64.