Actually the differences are a lot more than that, but it basically depends on your uses.
The macbook is a lot more cheap, but also is much more compact the a MBP, meaning if you traveling with your laptop, the macbook is much more efficient.
But otherwise the macbook screen is much smaller than the MBP's and is less comfortable when it comes to creative production (such as graphics, music production, etc...).
By performance, the macbook will fit anything you want unless it's some heavy weight stuff like pro music editing or some serious graphic design (the only real difference is the processors!!).
For games the macbook can't compete with the MBP only cause of the video card.
So if you like the affordability, mobility and performance for basic stuff and up, go for the macbook (I work with a 2.16Ghz 3GB-RAM macbook and it runs Photoshop, dreamweaver, World of Warcraft, and everything perfectly!).
If you want better performance, games and willing to pay $500+ more, just go for the MBP.