Graphic novels and comics are often confused, but are not the same thing.
Graphic novels are usually presented in a comic style format. However, they can be fiction, non-fiction or biographies... Fantasy, Realistic or Historical... and every genre in between.
Graphic novels are usually full length, stand alone stories, even when part of a series, with complex themes, plots and characters, which use a combination of images and words to narrate the story.
Novels with illustrations are not graphic novels as such, merely novels with a graphic component.
Manga is a specific form of graphic novel, with a rich history and tradition in Japanese culture.
In a word - no.
There has been a lot of research into the 'dangers' and 'benefits' of reading graphic novels - and the consensus is:
One of the key goals for the NIST Libraries is to promote 'Reading for pleasure' and to foster a reading culture within the school. Reading books that interest us and entertain us, is one of the best ways to practice and develop our reading skills in a meaningful and personal way. This includes graphic novels, non fiction and audiobooks.
Trying to 'force' students to not read what they value and enjoy, in favor of what adults see as educational or worthwhile, can lead to students losing the desire and motivation to read.
Let students read! Make suggestions and recommendations - absolutely - but don't 'make' them read books they are not interested in or do not enjoy. Free choice is important for the reading growth and development of our students.