Not sure of the difference... I don't remember seeing the regular Pump in Style at the store. I have the Pump in Style Advanced and love it. My only complaint is that it isn't as quiet as I thought it would be from what I read. It's okay though. I think the Metro bag model has a removable pump, which would be great, but I didn't get that one. There is a 20% off coupon for BRU for Medela pumps this week... if you're considering buying soon here is the link... https://trus.imageg.net/graphics/media/trus/112809-bru-weeklong-cpns.pdf I'm all for saving $$.
I have the PISA and love it. Advanced has the 2 phase pumping thing (short and quick to let down then longer deeper sucks, more like a baby sucks), I don't think the PIA does.
I have the PIS & its okay. I know a lot of people really love the Medela's but I never seem to get a lot of milk when I pump, so I don't know if its the pump or my body. I know I make more than the 1 oz I end up pumping!
Re: What is the difference between these two pumps?
I have and like the pis