I don't speedrun this game personally, so it isn't really important to me personally but I do watch WW Speedruns from time to time, and I noticed there was a new category called Any% No Barrier Skip, but isn't that the same exact route as if you were going for all dungeons? probably a silly out-of-touch question to ask with a very simple answer, but I was just wondering if there was a purpose for having separate categories here.

It's because All Dungeons uses Barrier Skip.

In all dungeons, you indeed do Barrier skip after Forsaken Fortress 2. This results in a shift from any no BS. The big changes are getting light arrows early, having the fully powered up master sword and mirror shield (skipping 1st half of Earth temple), and opening a portal so you don't have to do the whole triforce collection quest. That's the biggest difference imo