Beyond Balderdash is the expanded second edition of Balderdash. Balderdash is based on bluffing your opponents into guessing your false definitions to obscure words. Beyond Balderdash adds several new categories to the mix: Movies (make up a plot), Dates (say what happened on it), People (say what the person did), and Initials (make up what they stand for). The real answers are often even more outrageous than the bluffs, so the game offers plenty of laughs.
The UK version of Absolute Balderdash is a different variation with different questions. Notably, the UK Absolute Balderdash features a "Law" category, where you complete the law given on the card. Beyond Balderdash is lacking that category, and features in its place a "Date" category, where you are given a date and must come up with the historical significance. The Canadian and Australian versions of Absolute Balderdash also feature the Date category instead of Law.
Absolute and Beyond were merged into the game Balderdash at least by 2003 (there is a 1997 edition of Beyond Balderdash still with the Dates category). Now, the vanilla version of Balderdash is the five-category edition with Laws instead of Dates. Balderdash with a single category (word definitions) has not existed since at least 2003.