Breath of the Wild impressed with how vast everything was, but there was lots of empty space. It worked for that game don't get me wrong, it's one of my favorite games of all time. TotK is so dense with content and creativity that it does make the original feel empty and small in comparison. It's a lot like Elden Ring in the sense that you can just pick a direction you've never been in and you'll just stumble across interesting things within 30 seconds.

It's not exactly the same map. They did a lot of improvements to it and added a lot of depth, even ignoring chasms and sky islands.

It uses the same map, but with more depth — there are at least two layers I've discovered so far — original Hyrule and Sky Islands — and I suspect at least one more :)