Both have you do the packing, but the loading and transport differ. A self-pack container sits in your driveway for days. A you-pack-we-drive freight service parks a trailer briefly, then hauls it fast. Loading comfort versus speed and price.
Verdict: Self-pack container for a relaxed loading window and built-in storage. You-pack-we-drive freight for the cheapest fast long-distance move when you can load on a tight schedule.