When you're expelled from your school you can go back to school again but to go back to school you must choose a different school to go to.
Being expelled means that you're not allowed back at the school you're expelled from but there's other schools that you can choose to attend.
Being suspended from that school means that you cannot go back to that school again until the suspension is over with but may return to that school again after the suspension is over.
So if you're expelled from the school you can choose another school to attend.