Threaded Jewelry refers to pieces that you have to screw in order to tightly fasten. Non-Threaded Jewelry will be hinged hoops, clickers, captive bead rings, and stud earrings (pieces that don’t have any screw mechanisms).
'Threaded' refers to jewelry which has balls or ends that require screwing onto a post.
There are two options when it comes to threaded body jewelry: Internal Threading and External Threading. With Internally-Threaded jewelry, the shaft is the "female" part of the jewelry, and the "male" part of the jewelry is attached to the decorative end(s) or balls. Externally-Threaded jewelry has threading on the bar or post.