Yeah that's a big difference. The regular seats are a much different story.
I've never done it but I read about how it's basically 3 days of sitting shoulder to shoulder with someone and there's no showers. Can't imagine what that would be like in a car filled with 50+ people.
I did take the Amtrak from CT To Boston once and it wasn't too bad, but that was a few hour trip. Much different than a few days.