Has anyone else noticed there are different "degrees" of Blindness immunity?

The specific case that brought this about is the Eversight Ring vs the Helldusk Helm. Both say that they give you Blindness immunity, and the Helldusk Helm even specifically mentions that it lets you see in magical darkness.

But this is not true.

If you have the Helldusk Helm equipped and you stand inside a Darkness spell, the spell is still treated as a solid object by the game for the purposes of spell casting and ranged attacks. You cannot shoot or cast outside of it unless you move out of its area of effect, which is functionally the same as being blinded. The only thing the Helldusk Helm's "immunity" actually prevents is enemies having advantage on attacks against you. Functionally, you are still essentially blinded by Darkness.

In other words, for the purpose of using Darkness defensively, the Helm is all but worthless.

Not so with the Eversight Ring. With the ring, you can sit in Darkness and shoot or cast out of it as if it wasn't even there.

I can only assume this is a bug, and that either both items were intended to give you the same effect, or, given the in game description, that the Helm and the Ring got their effects mixed up, and it's the Helm that is supposed to let you treat magical darkness as if it doesn't exist, while the Ring was just supposed to make you immune to the Blinded status.

Just a weird thing I noticed. I'd kind of like to see if there are other weird exceptions like this. Are there other blind immunity items? If so, has anyone tested them to see which "kind" of immunity they grant you?