It's just a Superman from a particular continuity.
Morrison's t-shirt Superman is slightly different from the Superman we currently have. The Superman Bendis is writing, that Tomasi and Jurgens wrote, has a lot of similarities to t-shirt Superman (Nuperman) and a few points of shared backstory, but differences too.
Just like the Donner Superman is different from the Snyder Superman, but both characters are still Superman.