Photo Eye-Q Lite
I imagine this game is better on the I-pad than on the i-phone simply due to screen size. This game reminds me of an adult version of Where's Waldo.
They give you two busy and detailed images, landscapes, animals, etc. They appear to be the same, but you have to find what is different. One has a tree in the background, the other doesn't, etc. Tap your finger on the part of the image that you think is different.
The app also gives a hint or two if you are stuck. To be honest, I found it to be a little bit difficult. I hope to improve with time.
Also, I think this is a great learning tool for kids who need to improve their concentration skills and attention to detail!