I’m only concerned about the overlap. Some easier ferratas (A, B) are frequently used without any equipment. Sometimes they have simply evolved from a harder path with security ropes and/or ladders.
I’m in doubt what tag they should have. Some people might get upset if their favourite paths disappear from the map. However, when renderers support this tag, it is very useful to clearly identify secured sections on a map. Which OsmAnd does as of recently. Having a grade displayed would be even better. A/B ferratas are also a decent way to come down after climbing.
As for the distinction, I don’t see much point in separating. After all, should we have a category for the original ferratas, that were built for military purposes? They are a climbing aid. Some routes can be passed around on foot, some not. But there’s no distinguishable feature that would separate them.