Which of these 2 graphics cards is better and by how much?

I'm deciding between two graphics cards here (AMD Radeon HD 7650M & GeForce GT 640M) and was wondering which of the two cards are better and by how much is the superior card better than the other.

Both mid-range graphics, but I'd go with the Gefore card as it even seems to top the 7670.

It would also depend on the price and what the Laptop is being used for.

The 640M is alot faster according to notebookcheck.com