You use 'during' with a noun. For example, 'During the film, I ate popcorn'. Other examples: During the war, many young men died. During dinner we talked about our day. During the holidays we swam in the sea. You use 'while' with a verb.' For example, ' While watching the film, we ate popcorn'. Other examples: While fighting for their country, many young men were killed. While eating dinner we talked about our day. I hope this helps!

Hi Fabien, there is an easy rule to follow here: Use "while" if you have a verb or a verb in -ing form in that clause, : "While I was reading a book..." "While reading a book..." Use "during" if what follows is a noun, such as: "During my summer vacation..." In other words, while is somewhat like "pendant que/alors que" whereas "during" is like "pendant".