Yeah, I know Petsmart do the online price match which is quite nice of them to do it, however, I don't think Petco do it anymore, last time when I was trying to online price match with Petco, they are trying to add 8 dollar shipping on top of it(which wasn't very nice of them), I got away with it luckily and recently I also noticed Petco.com specificaly stress that it's "Online price" only, which leads me assuming they won't do online price match anymore...
I agree with you that they both do carry different products, and Petsmart is usually cheaper, and cleaner too. But just for the price match, I would definitly go for Petsmart