the 20 million are obviously shiments, since that is what labels track and what matters.
i guess huge amounts were shipped for christmas, of which the album still sells. now new shipmentys are due because of the GIGANTIC post grammy sales, and within 2 weeks the 20th million copy has been shipped.
and these days, in contrary to the 90's, labels doesn't ship much more than than the retailers expect the album to sell pretty much at once, because retailers can't afford big stocks of un-sold albums. that's the reality today.
but i guess the album has sold close to 19 million copies to end-customer including this week
QUEEN 