“I guess the basic difference is that animation is sequential in time but not spatially juxtaposed as comics are. Each successive frame of a movie is projected on exactly the same space – the screen – while each frame of comics must occupy a different space.”
-Scott McCloud, “Understanding Comics”
Anime, and animation in general, has it easy sometimes, specifically in its ability to portray movement as opposed to a drawn medium like manga. This isn’t to say that manga is unable to show the reader how its subjects move; however, it has to work a bit more to be effective.