Spot Differences HD Lite is the iPad version of a well-made hidden differences game on the App Store -- featuring a number of well-made puzzles. It's not the best or most advanced such game on the App Store, with a fairly rudimentary design and limited number of options, but the quality of the puzzles, relative challenge, and the integration of timers and availability of a "relax" mode make it a fun app for anyone who likes these types of puzzles.
When you start the app for the first time, you can choose between Relax and Challenge modes. The former has you completing these puzzles without a timer. You can still fail, however, if you get three red X's signifying that you missed those particular guesses. The Challenge Mode adds a 100-second counter that limits how long you have to solve these puzzles. The reason Spot Differences HD Lite is a good entry in this genre is that it manages to be challenging without being impossible. Differences are subtle, but they are visible once you spot them, and they are always thematic. There are no tubas hidden in an ocean reef in this app.
For those that enjoy hidden differences games or mind benders in any format, Spot Differences HD Lite is a great game. It's quick and easy to play, offers a lot of different stages, and has great replayability, all without being too easy or too challenging. You'll find yourself coming back to this numerous times until you spot all of the differences.