"popular" is an industry genre , as in "jazz" "classical" , not a reporting of massive sales of any kind of discs. In all honesty half at least of the music filed under popular is dire. In the uk although derived from Popular "Pop" is sort of different being generally more upbeat with the likes of Rock as sub genre. Perry Como and Donald Peers were "Popular" Artists, the kind of whoms LPs you bought for you mum's birthday