Gaga was always bigger than Britney globally so her. Poker Face was bigger than any Britney song (in the US and globally), Gaga also being a massive name the last few years whereas Britney hasn't really had a massive WW hit since 2004 with Toxic. Gaga is also the bigger global touring act (by a huge margin

), you can't compare album sales considering Britney debuted in the 90s and Gaga debuted in 2008