Sting is correct - AB was released in Nov. 1991. So ALL of its sales would have counted for this "year end chart" come 1992. HTDAAB holds no advantage in that aspect.
The difference is that early on AB was promoted only by "The Fly" and U2's reputation. "The Fly" was a marginal hit in the U.S., at best. AB debuted at #1 mostly because it was U2. AB then lingered near the top on the strength of "Mysterious Ways" and "One".
In contrast, the ubiquitous "Vertigo" enabled HTDAAB to debut with an enormous first week, and the holiday sales kept it near the top. Sadly, subsequent singles were horribly promoted in the U.S. - the worst promotion I've ever seen (I'd fire U2's marketing team). Only when U2 did the second iPod commercial did HTDAAB start making a reappearance in the Top 200.
Regardless, the fact that in an era of horrible CD sales (back in '91, albums, tapes and CD's were sold - no mp3's were available), U2's album is still in the Top 10 for the year. Heck, JT only finished #3 for the year in 1987!! And as we saw, AB finished #5. This shows U2 still is wildly popular, even many years into their career.