<em>During</em> is a preposition and takes a noun: 'She left during the meeting.' <em>While</em> is a conjunction and takes a full clause with a subject and verb: 'She left while we were meeting.' They express the same timing; the difference is what can follow them.
The core difference is grammatical, not temporal
Both words place one event inside the span of another. The choice between them is decided entirely by what you want to put after the word.
- During + noun phrase: during the film, during lunch, during the war, during my shift.
- While + subject + verb: while the film was on, while we ate, while I was on shift.
You cannot mix them. 'During we ate' and 'while lunch' are both ungrammatical.
The test
Look at the next few words. Is there a verb with a subject? If yes, you need while. If it is just a thing or an event named as a noun, you need during.
If you have written one and it does not fit, converting is straightforward. Turn the noun into a clause — 'during the storm' becomes 'while the storm raged' — or compress the clause into a noun — 'while we were negotiating' becomes 'during the negotiations'.
The one real exception
While can be followed directly by an -ing form when the subject is the same as the main clause's: 'She took notes while listening.' That is a shortened version of 'while she was listening', not a case of while behaving like a preposition. If the subjects differ, you must spell it out: 'She took notes while he presented.'
The other meanings of 'while'
While also means 'whereas', setting up a contrast with no time element at all: 'Sales rose in the north, while the south flatlined.' This second sense is common and perfectly standard, but it can collide with the temporal one. 'While the report was being written, the policy changed' — did the change happen during the writing, or in contrast to it? Rewrite if the ambiguity matters.
During has no such double life. It is always about time, which makes it the safer choice when clarity is at stake and you can phrase the second event as a noun.
A useful nuance
During can mean either 'throughout' or 'at some point within'. 'It rained during the match' most naturally means at some point; 'the alarm sounded during the whole evacuation' needs the word throughout to be clear. If you mean the entire span, say throughout.
Note too that whilst is a British variant of while. It is correct but reads as formal or old-fashioned to many readers, and has no equivalent in American English.
Frequently Asked Questions
Is it 'during I was working' or 'while I was working'?
'While I was working.' 'During' cannot be followed by a subject and verb — it needs a noun, as in 'during work'.
Can I say 'during the time that'?
You can, but it is wordy. 'While' says the same thing in one word, so 'while the machine was running' beats 'during the time that the machine was running'.
What is the difference between 'while' and 'whilst'?
None in meaning. 'Whilst' is a British variant that sounds formal or dated to many readers; 'while' is standard everywhere and is the safer default.