OK I was slightly wrong before, the All Folders type applies to both Opus and Explorer, which is why it allows non-Opus things to be defined as well.
All Files is something only Opus has, so Explorer would not understand things you added there, making it pointless to allow non-Opus commands.
You should still generally ignore the other Folder type. I'd have to do some digging to explain exactly what the distinction is but the result I know: Just ignore it, and use the ones at the top.