GP2 and GP3 are tied together. They are run by the same organisation, share the same hospitality awnings and plenty of teams compete in both categories.
Inevitably, the majority of those making the top 10 compete in GP2. Logically so, given that this is the senior of the two categories.
But as Daniil Kvyat and Valtteri Bottas, who both made the leap from GP3 to F1 in recent years (admittedly, via a year of Friday driving in the case of the Finn), have proved, the level of drivers at the front of the 'lesser' category is still impressive.