Idk exactly since I do local. But from everything I hear, you basically still work for the company that leases it to you. Often you can still use all of their mechanics too. They just pay you more $ per mile but you have to make truck payments back to them. The trucks will still have the company's name on them and everything.
There are some horror stories with it like everything else, but if you are willing to work and get miles, then you can make way more than driving a company truck.
Even guys who outright own their trucks often will technically work for another company. It's confusing legal stuff but makes it so the driver doesn't have to worry about the business side of it so much. But they pick their own loads, can go home whenever they want, and make bank if they do it right.
One dude who lurks another board does this and still clears like $100k and is home most nights because he runs a lot of regional loads. If he were out for a month at a time, he could make $200k easy.