Thats a stupid comparision, Rihannas first hit big in 2005, Katy has really only been around since 2008. Rihanna has had twice as much time to establish herself, plus she has had 6 albums, katy really only has 2 ablums. How about you ask this comparision in 2-3 more years, then i would actually be able to compare the 2 artists. DUMB QUESTION!!!!