The one in the body folder is the body created from the sweep feature and is named from it.
Since you're selecting from the graphic's area tree, I'll assuming you're in the middle of a command, but I don't know which one.
But being in mid-command I think is why it's requiring a body and not a feature.
So what are you doing when this happens?
This is a correct behavior, the name suggested is Feature tree and not body tree. This means that you use features to create a body and for some commands you cannot select a body by selecting the feature (as there might be more feature associated with that body).