What is the difference between the A2 CofC and the GVC?

The A2 CofC lets you fly closer to people than the basic rules allow. It is the usual next step once you have your Flyer ID; you study it online, and most people finish within a fortnight (though lots finish within 24 hours of purchasing it!).

The GVC is the broader qualification. It opens up operations the A2 does not cover, in something called the Specific Category.

It's what you need if you intend to work with larger, heavier drones, closer to people and in built-up areas.

If you'd like to know more about the GVC, and the upcoming 'RPC-L1' qualification, Matt explains the difference here:

Most people start with the A2 and move to the GVC when the work demands it. You can also do both, and neither is legally required to fly commercially.