There is a difference but subtle to the learners. It is semantically awkward to say: Sorry I was in the shower while you called me. But it is perfectly fine to say : Sorry I was in the shower when you called. While - (to me) usually suggests one event taken place within the same time frame of another, i.e. While I was in L.A. for a business conference, I visited Disneyland. In this contexts (or t