It is different, because range can change depending on external factors you have no control over. You can charge the car thinking you have 300 miles of range, and you do. Then you make the same trip again, but an overnight frost takes a huge chunk of that away from you, and now you can't make it back. That's the apparent situation, anyway. It won't happen often but can happen in special situations: ski trips, having to park your car outside due to lack of indoor spots, an extra day in the airport parking lot, etc.