When he quit in Beyond, he had a full career behind him and was clearly compromised by his age making him desperate enough to rely on a gun. He fought as long and hard as he possibly could.
I think that's the big difference, and I think it's most people's gripe. Nolan/Bale's Batman hardly did
anything comparatively in his career before hanging it up seemingly for good - twice.
He never evolved into the mature Batman we knew and loved as we had been excitedly waiting for (in fact, he de
-matured for the sake of adding drama to the plot), and even though it says 8 years pass, it still feels like he's just getting started.
Not to mention, nothing Batmanny happens in that 8 years. Then he trains a whole lot, gets kinda lucky to smash Bane's mask tube, Catwoman shoots Bane, and Batman quits again, very probably for good. A little underwhelming. No ride into the sunset to continue the endless crusade, no satisfying philosophical triumph over Bane.. it was just 'WHEREZATRIGGEHUR, oh Catwoman killed you suddenly, woops... time to fake my death, I've had enough', which is all pretty un-Batman-like.
It was a huge waste of potential for a budding franchise that had a whole world of stories and characters to explore and re-interpret beautifully, and his choice both times seems barely substantiated.
This is what differentiates it from Batman Beyond. That Batman had a proper career behind him, and he behaved like Batman.
Not to mention, he didn't just dump the cave on Terry and run away as Bale's Bruce did Blake. He raised
Terry hands on, guided him. He realized the importance of his involvement not only as a continuing contributor to Gotham as Bruce Wayne, but as a mentor to his successor in this never-ending mission. 'The war goes on.'
One more note - The Dark Knight Returns depicted the concept before either of the two. You can see influences from it in both! I do love that about Rises.