I was explaining some of the delineations in writing YA versus MG versus adult books on a list I'm on and thought it might be helpful to post here as well.
Middle grade are emphatically kids books, ones written for kids about kid-like experiences. They can touch on tough things and sad things, but once it touches on anything very dark, it automatically becomes YA. There is a very strong protective bubble around middle grade stories.
Because middle grade books are short 20,000-45,000 words, their scope is much narrower and often the internal and external struggle are very strongly linked or intertwined. Books can be about trying to find a friend or simply objecting to a new move or school. For one, these books are so short, but two, those are the issues kids are dealing with. The range and scope of the actions a kid protagonist can take are greatly limited when compared to those of an adult, and kids need to see themselves reflected in the choices and actions of the main character. Even so, the best of middle grade is still multi-layered, even though subplots are kept to a minimum and interact even more firmly with the main plot than in adult novels.
One way I think that kids books can be different than adult books is that many of middle grade and YA books start with the protagonist NOT wanting something because for this age group, so many of their choices are made for them. Often part of their journey is learning how to make the best to those choices, or learning to live with them, or altering their perspective, or coming to understand how it was actually a good thing.
From a writing mechanics standpoint, MG is almost always told in a single POV.
All the elements of writing good fiction apply to both categories. As I mentioned in the last post, in YA, all literary devices and approaches are available to an author. There really are no limitations.
A lot of the single focus present in MG in terms of plot lines and subplot still exist in YA, but they can be broader if the story demands and supports it.
In YA books, a lot of the protagonists are often still having choices made for them, but they are in the act of claiming some of that power for themselves in a big way. The ways in which a 16 yo can take action are much different and more pronounced than the ways in which a 10 yo can take action, and the books reflect that. They are often about that moment when a teen recognizes they can seize the reins of their own life.
Teens are standing on the cusp of having to make all their own choices, often after years of having choices made for them, so seeing an active—or even a passive—protagonist learn to make choices and then suffer through the consequences of those choices, wherever they might lead, is a key component.
YA books, for many teens, are really safe places to experience a wide variety of things without any actual risk. Kids this age are overwhelmed by their emotions and want to see how others deal with this emotional tsunami that is adolescence, and books are a great place to do that. Which is why it is so ironic and irritating that so many clueless adults are afraid some of these books will give kids “ideas”, when in fact, they act as more of a safety valve. Or serve as a warning.
Teens want to feel emotions in a safe environment, and books allow them to do that.
The funny thing is, while the trappings of being a teen change radically from decade to decade, the core emotions and experiences remain surprisingly constant: friends, fitting in, first love, sexual experiences, defining oneself, coming into personal power, dealing with the mess parents have left behind, the scariness of impending adulthood—all the same stuff we dealt with in our own adolescence. So an ability to access one own’s inner teen is hugely helpful here.
My own opinion is that those core emotions serve as the wide portal for the stories, the big welcome mat that allow teens to connect with so many different types of stories, stories that the adult market considers entirely different genres.
I also think because teens are so fascinated by their own emotional world and sort of define narcissistic, more introspected and inner journey oriented books can do really well for this reader. Readers at this age really want to experience that angst along with the characters; they want to dwell in an emotional landscape.