@murrayjames

They are interchangeable when the students deliberately don't attend class. But 旷课 means "不请假而缺课"- not going to the class without informing the teachers or school. So sometimes it could be the students forget to do that or get too sick and can't ask for a sick leave in time. So 逃学/逃课 sounds more serious than 旷课. “逃” is deliberate. Hope it helps out.