I would say there is a great deal of variation -- but one must know which anime stories to watch to see it. I would suggest you try and watch "Princess Mononoke" sometime as an example of something which is anime, with a good story, and also one of the better animations done for any animated film, imo.
I think a part of it is that anime looks a lot alike, because many elements which make it, itself, comes from the culture and different style of art, which makes some elements look like it is all the same animation -- but I would think they might think the same for most american animation.
