You should have a look at this thread.

Alain

https://www.researchgate.net/post/What_is_the_difference_between_carbon_quantum_dots_and_graphene_quantum_dots

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.

various types of C-dots have been synthesized and they can be

morphologically classified into two major types, graphene-based

quantum dots (GQDs) and amorphous carbon nanodots (ACNDs).

In most cases, GQDs mainly consist of an sp2 carbonic nanocrystalline

core with surface defects or passivation. Unlike GQDs, ACNDs

comprise a disordered carbon framework integrated by coexisting sp3 and sp2 hybridized carbon moieties with the possibility of surface

functionalization. This irregular configuration is probably

caused by relatively higher amounts of oxygen/nitrogen containing

moieties that disrupt the systematic carbonic framework though

covalent bonds

for more information please refer to following references:

Data High Performance Photoluminescent Carbon Dots for In-Vitro a...

Article Opportunities and Challenges of Fluorescent Carbon Dots in T...