Normal baler has just a ramp for the guy on the wagon, he/she pulls it off and stacks it. This thrower is an attachment to the New Holland Super 68 baler, that replaces that simple ramp. It also takes a tractor with more horse power to drive that thrower, as well the special wagon with the sides to keep the bales contained.
There's also just let the bales fall off the baler, and then either have someone driving a tractor, someone picking up bales and handing them to a stacker standing on the wagon.
I've also seen custom equipment that the operator drives along, it picks the bale up, puts it into a que, then moves it over to make another column, after that matrix is full, it rotates all the bales and pushes them back onto the machine, and starts to make another matrix. I think I've seen the New Holland trade mark on those. But it's a machine that only does the stacking, and has an operator station. I saw them used out in the Idaho, Western Washington, from driving on I90/94.