If you don't specify an end-time then the following logic is applied:
For a live store (one that's currently recording), the playlist presented to the player is a live playlist.
For a recorded store (one that isn't recording), the playlist presented to the player is a recorded playlist, using the end-time of the recording.
I'm not sure if that answers your question. The end-time for a stream that is live is obviously different (as in it doesn't exist) compared to a stream that isn't live and so has an actual end-date. DVR treats streams differently depending on if they are live or not.