A McGuffin tends to be more portable and useful. If a giant pyramid that can raise the dead appears, it's a BDO. If the dagger that will end the universe needs to be taken to Alpha Centauri, that's a McGuffin.
Oddball pick on my part, but where does the Star Rod from Kirby's Adventure fall in? Both? For context; it's like a BDO in the sense it powers Dream Land's dreams, but like a McGuffin as it was split into pieces and collected throughout the game, and ultimately used to fight the final boss?
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Also, in Australia, BDO is the Big Day Out.
https://youtu.be/ABPPF0Eyd3c?si=UJ-24_m8VVIVXRPl
See also, Donald J. Trump
https://tvtropes.org/pmwiki/pmwiki.php/Main/BigDumbObject