Time Clause

[sergeyrais]

Are the conjunctions WHEN and WHILE interchangeable in the clauses of time containing a verb in the Past Continuous Tense?
e.g. While I was going along the street, I met my friend.
When I was going along the street, I met my friend.

[sergeyrais]

We use both when and while as subordinating conjunctions to introduce adverbial clauses of time. They mean during the time that and indicate that something is or was happening when something else occurred:

• The prisoners escaped when / while the prison warders were eating their lunch.
  
• When / While the prison warders were eating their lunch, the prisoners escaped.