Which Mac? Ibook or Pro

[CapriD]

I am looking to getting a Apple Laptop. NOt keen on the new thin one they have so its down to the ibook or the pro.

Now, I will be using it for the internet, a bit of word but I will have a fair few picture on it and I will be using photoshop now and again to edit pictures.

I am confused at the big difference between the ibook and the pro. I like the 13.3inch screen on the ibook but the Pro I would be looking at 15inch. Is the pro worth the extra money? Cheers