In general CQD and GQD look like the same, just like a cousin, however if you examine throughtly by searching its crystallinity. It seems they are different and also their both energies and properties (see the references regarding quantum dots)
GQDs have sheet like structure (2D), whereas CQDs are like nanoparticles. Also GQDs may have some functional groups (such as -COOH or -OH) attached to the sheet based on synthesis method used.