You all are shading Demi (who is clearly doing bad) but it's not like Selena is doing good at all. Video, much airplay and it's about to fall from the top10.
Applause wasn't a complete flop. It did decently, reached #2 (only blocked by Roar ) and stayed in the hot 100 top 10 for a decent period of time. I don't see either song being bigger than Applause, but Selena has more chances to pull an Applause than Demi.