One of the most notable aspects of manga is its wider range of genre and target audience/demographics.
There are far more selections for
females--
elementary school,
junior high,
high school,
college, and
adult--in manga than in English-language
comics.
Shoujo manga refers to a relatively small
subset of this group, but when used outside of
Japan frequently indicates the entire range. And no, they're not all
romance stories. They include thoughtful
science fiction,
sports action,
fantasy, etc. etc. (Oh, and also
soft porn. So much for the
Euro-Americocentric idea that
women are turned on verbally, men are turned on visually.)
Manga artists (usually, but not always, also the writers) tend to employ more advanced
storytelling techniques. For an interesting analysis, see
Understanding Comics by
Scott McCloud. Other interesting books include
Manga! Manga! and
Dreamland Japan, both by
Frederick L. Schodt.