Just because children are the same age it does not mean they will act and behave in the same way.
We can not really compare the children on the way their behavior is just because of their age.
A lot of things have to be taken in account for how children social and emotionally develop.
If they have older siblings or if they are a only child can help in understanding part of their social developement. If they are a only child it could explain why they don't want to share toys or books. Sometimes only child family have no one family or friends in the area with children to learn to share.
A child's developement also can be affected by their living situation and things going on in their lives. We as educators have to sometimes have to redirect the behavior of the children. A child throwing toys at their classmates has to be redirected about the behavior the are exhibiting at the time. We can talk to the children why we don't throw toys in the classroom and that is not a safe way to play with their friends. By talking with the child you can find out why they are behaving in the matter they are exhibiting.
Sometimes children are just shy and won't talk to you are their classmates then you need gain their trust so they beome comfortable with you and being in the classroom.