I have been a fan of graphic novels, such as comic books and manga, for a while now and I have noticed some big differences in the ways that the stories are told. First, the most obvious difference is that you read manga in the opposite direction that you would read a comic book, which can mess you up a lot.
This often affects those who are used to reading left to right for everything. Reading in the opposite direction sometimes caused me to skip a couple of conversation points, until I was confused enough to realize my error. This difference is very minor, however, since it does not effect the storytelling, simply comprehension.
Graphic Style
The one big difference between most comic books and manga is that, in most cases, unless the manga is a volume edition, it will not be colored. This is unlike comic books, which are almost always colored. However, there are, of course, exceptions in both categories. This makes a huge difference if you are already used to one style and it might make it a bit confusing. For example, you will not see a mention of color occur very often in manga, which does affect the storytelling in some ways.
Issue Order
Now, comic books and manga have both existed for a long time, but it is more difficult to follow your favorite comic book characters. For example, there have been many revisions of Superman's story. In one, he is the classic Superman. In another, he is married. In some, he is evil. There is one where he crash landed in the USSR instead of America. This makes it harder for people to follow their favorite comic book characters.
In manga, while there are sometimes different versions of the same story released, they are in much less common and are much easier to follow. Most of them are clearly labeled with both issue number and version title, whether it is a prequel to the original story or something different. However, there are few alternate universe manga that have been written. One notable exception is a manga series called "Alice in the Country of Hearts," which is a manga adaptation of a video game based off of Lewis Carroll's "Alice in Wonderland," where the many different endings of the game were adapted into different volumes of the manga.
Story Choices
The final note on the differences between these two styles is what kind of stories these graphic novels tell. For example, comic books sometimes grab popular western books and television shows and make them into comics. Manga writers do that, too. They pick up popular things made in the west and make them into a manga. However, very rarely do I see a comic books made of something that is popular in the east.
There are great stories in both worlds and I enjoy reading both styles. However, lately, it has been an easier task to follow stories written in manga style rather than comic books. With all these alternate universes and re-imaginings of my favorite characters, it just got really hard to follow. Although, I shall never give up on my favorite character, Superman.
