Studios fall into three basic categories, Home studios, Project studios and Commercial studios. It's pretty obvious what a home studio is. Many people working in the music industry, and even the TV and film industries, have their own studios at home. They put them in the spare room, the garage, the basement, an outhouse - even in a corner of a bedroom sometimes. And there is no reason why a home studio shouldn't produce recordings that challenge top commercial facilities. Obviously in a top commercial studio helpful staff will make it easier for you to do your best work, the equipment and acoustics will be first class, and you will probably be working with top musicians too - there may even be a restaurant and bar! Of course the top studio is always going to be that little bit better - but it really is just a little bit. You can do professional work in a bedroom. Sometimes simplicity sells, and you don't always need a twenty-four track studio to make a song demo or a soundtrack for a documentary.
There really isn't any difference between a home studio and a so-called project studio. A home studio is a project studio that you have at home, so that's easily dealt with. So what's the difference between a project studio and a commercial studio? Simply, a commercial studio is available to all comers at an hourly or daily rate. Make a booking, do your stuff in the studio, pay the invoice and collect the tape. A project studio is something owned by one person, or maybe a partnership, where the owner or owners work on their own projects. The owner may be a musician working on a CD, or a composer working on a TV soundtrack. Commercial bookings are not welcome in a project studio because a) they are taking up studio time that the owner would probably rather use, and b) once you start hiring your studio out as a facility you become involved in many more health and safety regulations and your insurance premiums will probably go through the roof.
What people do in their project studios is of course literally their own business! But I have identified at least five distinct categories of project studio. Take a look at what you can achieve, if you have a mind to...