According to the dude that runs top shelf, via the hightimes video on their lab, anything above 5% moisture content will "autobudder".
In the same video they talk about how that if the customer wants budder they just take the shatter and "whip it up".
Wax imo is what you get when there are too many undesirables and low purity levels. Shatter or budder can come from nug and trim run and is highly pure, budder being less potent by volume but I prefer budder as it usually has more flavor.
Also, to answer the title question, it depends on who you ask and where they live, hehe. A lot of people, even around here and in shops, call anything translucent and amber "shatter", but half the time it's more like taffy, etc.