This appears to be a simple misunderstanding. This archived CNN article, retrieved by a simple Google search, seems to clear up this dispute entirely. It confirms that the RIAA did indeed officially honor the album as the "top-selling album of the century", but it only factored in US sales. The article specifies that Thriller sold 6 million more copies than Greatest Hits in terms of worldwide sales. I originally missed what Piriczki was saying too, but they do in fact specify "in the US", a claim that appears to be correct, despite the fact that it's not the greatest-selling album of all time (this claim is not being made at all). Are we good here?  X