Might want to rethink that. Both of them had albums in 2011. Adeles sold 6 million in the US alone, 17 million worldwide. Beyonces sold just a little over 1 million in the US, doubtful she reached 6 milly worldwide. Can't find that figure though.
Both of them had albums in 2008 also (Adeles first) and it seems both sold close to 7 million worldwide.