Difference between U8180 and U8160?

In simple terms, what is the difference between the U8180 and the U8160?

I'm looking for a couple of cheap phones for my daughters, and I can get the T-mobile Rapport (8180) for £50 or the Vodafone 858 (U8160) for £42 without looking too hard.

So far as I can see, the specs are identical, same screen, same CPU, same memory....

Are the images interchangable?

thanks!