Throughout表示事情在整个事件节点中一直发生;During表示事情发生在整个事件的某一个时间节点上。
First Aid will be taught throughout the period tomorrow.
(This means the entire class period will only be on First Aid and nothing else.)
First Aid will be taught during the period tomorrow.
(This means that at some points during the class period First Aid will be taught.)
Throughout和during都可以用來表示事件在一段时间内连续或定期发生:
First Aid programmes will be held throughout the year.
Many soldiers were killed during the war.
Reference
Teo, Alvin. 2019. Confusing Grammar Explained. Singapore: Marshall Cavendish Education.