Check them out in person if possible. The other difference noone has mentioned yet is the screen. Edit, someone mentioned it while I was typing this(!) however it's not as clear-cut...
The MBP screen has a higher colour gamut, but unless you're using photoshop you may not care.
On the other hand the MB screen doesn't (I think, judging from photos, I've not seen one in person since the new model launched) have a shiny sheet of ultra-reflective glass in front of it. Some people love the glass. Others like me would rather use just about anything else.
Assuming I'm right and the screen is just plastic glossy like the previous model, I personally would find the MacBook screen far nicer, even if it isn't actually as good a panel underneath (which it isn't).
I'm not for a moment telling you which you should prefer - but it is something to consider, and hopefully test out in person if you're near a store.