there are various differences according to the model of either mb/mbp you choose. The macbooks are thicker with a more durable case and a smaller glossy screen. They also come in black or white depending on the model. The macbook is really your consumer travel laptop. It has 1g of ram as standard, no graphics card just shared memory and a smaller processor.
The MBP however has a different, more normal laptop keyboard, has an aluminium outer and is stronger than the macbook in just about all fields except for travelling. It comes in Glossy or Matte screen and can be 15' or 17'. The base model has a 128mb graphics card with the others with 256mb cards. It comes with 2g of ram as standard and it comes with various other features like a back lit keyboard, led lit screen in 15' models and is basically your graphics, desktop replacement laptop.
This is just a quick rundown but more can be found on guides.macrumors.com/Buying_a_MacBook_versus_MacBook_Pro or on apple.com