The problem with most anime is that you often find a different turn of events than the show portrays. Attack on Titan, displayed some minor differences in the manga from the show, but nothing major that would really change the course of the show.

Before i put anything to rest. Don't listen to the ones that say that the story the manga is telling is complete nonsense from the main plot. It isn't. The manga after a certain point moves onto observe the bigger problems that affect the walled city other, and then demonstrates how the events are connected. Though it may be a left turn from the Main plot of "Get to the basement and see what's goin on down there." It notes the problems and other obstacles that get in the way of the scouts before they make their expedition. For example a suspicious new type of titan, and various other things.