When is a conjunction of that.
As conjunctions the difference between that and when
is that
that is
Introducing a clause that is the subject or object of a verb (such as one involving reported speech), or that is a complement to a previous statement.when is at what time.
As pronouns the difference between that and when
is that
that is the thing, person, idea, quality, event, action, or time indicated or understood from context, especially if more remote geographically, temporally or mentally than one designated as "this", or if expressing distinction while
when is what time; which time.
As adverbs the difference between that and when
is that
that is to a given extent or degree while
when is
Used to introduce questions about time.
As nouns the difference between that and when
is that
that is something being indicated that is there; one of those while
when is the time.
As a determiner that
is the (thing, person, idea, etc) indicated or understood from context, especially if more remote physically, temporally or mentally than one designated as "this", or if expressing distinction.
As an interjection when is
that's enough,
a command to stop adding something, especially an ingredient of food or drink.