All purpose flour is bleached and has the bran removed. It's not healthy as all the good stuff is removed.
I think Unbleached flour has all or most of the bran removed but is not bleached. It's not whole grain but it doesn't have the nasty bleach in it.
I use almost entirely whole wheat pastry flour for my baking as
1 it is still whole grain and
2 has a smooth texture. .
For a lot of people when they first give up all purpose flour, they go to unbleached first and slowly move to ww pastry flour to avoid the "shock" of whole wheat cookies. We took the plunge before we even knew about unbleached flour and have been fine. But we aren't perfect. I have taken to using unbleached flour for pie crusts and brownies. The rest of the stuff we stick with ww pastry flour
HTH!