That's not really what that statement means. Instead, it means that PTR and Closed Beta participants are both playing on the same test environment/client. Which in turns that they can play and interact with one another. Pretty cool, right? (Previously, with other Blizzard betas and PTRs, participants played on completely different servers using completely different clients. So this is somewhat unique for D3!)
Client
That's not really what that statement means. Instead, it means that PTR and Closed Beta participants are both playing on the same test environment/client. Which in turns that they can play and interact with one another. Pretty cool, right? (Previously, with other Blizzard betas and PTRs, participants played on completely different servers using completely different clients. So this is somewhat unique for D3!)