There is no real difference, which is why it's absolutely idiotic to say, "oh, we're Early Access, that's why we can't release on PS4." It's completely on the developer if they don't want to clean up their code enough to submit for certification and then continue to improve the game after.
Of course it’s up to them whether they want to release the game in early access form or wait until an official release. They went with the early Access route and that’s why it’s not on PS4. You can have whatever opinion you want in regards to early access, it doesn’t change the reality of the situation. It’s not as if anyone is saying that if they lose revenue it’s Sonys fault, it’s just the reality of early access on PS4. That part is Sony’s fault though, just like MSs shitty indie scene was their own fault.
I’d imagine they’re working on the 1.0 release for both consoles right now.