Let's see, I gave several examples where you either can't use my where you can use subs

All subs have limits on their arguments.

or where my behaves different than subs do.

That's what you said, and I asked for that example. Repeating yourself doesn't help. The only thing example I see is that my() takes a list of variables for arguments, which just goes to show that it is like sub. Nothing else has arguments.