Superdelegates are honorees of each party. Governors, high level party officials, etc... who aren’t elected by the voters but are installed in the convention by the party itself. Demodog superdelegates comprise a major part of their voting at the convention. Republican superdelegates are far less numerous, and due to the way the GOP convention works, have far less sway.
Hitlery pretty much owns the Demodog party apparatus. That’s why she needs very little in the way of primary victories now - the superdelegates love the cash that the ‘Toon brings in from Hollywood and other celebrity sources.