>>1053589
There is quite a bit.
Originality and creativity for one. Too many American comics are just about guys punching one another in boring ways or a crime story that devolves into two guys punchline one another in boring ways. A lot of manga is about that as well, but people punching one another is usually done in far more creative and interesting ways, and most artists have their own spin on how combat is handled. Outside of that, many manga creators seem to have far wider range of interests and experiences than people making American comic books. What's more they use them in their work. You have manga about street racing, being a cook, rock bands, day to day school life, sports, gambling, and so on. European books have more variety than American ones.
Second is the paneling. Shape, size, and and placement of panels tends to be more flexible than in western comics and have more relation to what is going on in the panel itself. When you have an action in panels, they will often be angled and distorted to emphasize that movement. Small movement will often be in a smaller panel than a 'culmination' or a more significant, bigger action. Way panels are placed and structured in American and European comics is more restrained, with less connection between shape/size of the panel and its contents. That makes them feel less dynamic than most manga.
Efficiency when using text is another one. Text in manga is generally kept succinct and is used efficiently. Artwork and text usually exist in harmony and complement one another. In American comics, text is king. It is not uncommon to have sentences upon sentences in one speech balloon, or hacks who endlessly vomit speech balloons can become top billed writers. Most of that text is just useless information. Art is too often just there as a secondary supplement to the text, instead having art and text complement one another. European books are in between the two, generally being efficient with words as well, and both art and text complementing each other.
There is more, but these these are the differences that matter the most to me personally. Of course not everything adheres to the differences I outlined, but this has been a trend I noticed when reading comics from different countries and comparing them. I am aware that there are indie titles that do not fall in the same traps that most American comics do. I am also aware that manga is not perfect and has plenty of its own problems too.