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.
(Don’t use a time period.)
- He fell asleep during the presentation.
(When something happens.)
- During the winter we get a lot of snow.
- The kitten fell asleep while eating its dinner.
(Two things happened at the same time.)
- I read a book while Josie listened to the radio.