I am going to school. -I'm going to go in the school. I moving in the direction of the school, and when I arrive at the school's location, I'm going inside.
I am going toward school. - I'm moving in the direction of the school. - There's nothing implied here that says the speaker is going to go inside the school. The speaker could go inside the school, but using "toward" does not mean that specifically in the way that using "to" in "I'm going to school" means the speaker is going inside the school.
Student or Learner