Choose the difficulty level and find all 5 differences between the two pictures before the time lapses to unlock the next pair. Bonuses are awarded for finding the differences quickly so yes, speed counts. Remember that the differences change each time you play the game! So if you play D-Finder 3 once it doesn't mean that you can not play again and again! There are no hints so you really need to rely on your observational skills!
Use the mouse to interact.