We use during + noun to say when something happens. We don’t write a period of time with it.
We use while + subject + verb to talk about two things that happen at the same time. The events don’t have to continue for the same length of time, but they can.
- He fell asleep during three hours.
(Wrong, don’t use a time period.) - He fell asleep during the presentation.
(Correct, when something happens.) - During the winter we get a lot of snow.
- The kitten fell asleep while eating its dinner.
(Correct, two things happened at the same time.) - I read a book while Josie listened to the radio.
