strictly speaking, its the addition of the extra 5 letters and one space ...
There is no hard and fast definition of when a wide angle is considered "super" wide instead of just "wide". There are trends, but these change as technology changes the population distribution of available focal lengths for any given format, changing what is common and what is more rarely seen or used.
I would say that for APS-C format digital cameras (1.5-1.6x "crop factor"), focal lengths between 16mm and 20mm would be considered just "wide angle". Additional superlatives (e.g. "super", "extremely", ...) wouldn't apply until the lens covered something in the 10-12mm range. Given the common availability of 12-24mm and 10-20mm lenses for APS-C format, these superlatives only barely apply to this range these days.