Studios fall into 3 basic categories, Home studios, Project studios and Commercial studios. It's pretty apparent what a home studio is. Many people working in the music industry, and even the Television and film industries, have their own studios at home. They put them in the extra room, the garage, the basement, an outhouse - even in a corner of a bedroom sometimes. And there's no reason why a home studio shouldn't create recordings that challenge top commercial facilities.
Obviously in a top commercial studio, helpful staff will make it simpler for you to do your best work, the equipment and acoustics will be first class, and you will most likely be working with top musicians as well - there may even be a restaurant and bar! Of course the top studio is at all times going to be that little bit better - however it truly is just a bit more. You can do professional work in a bedroom. At times simplicity sells, and you do not always need a twenty-four track studio to make a song demo or a soundtrack for a documentary.
There truly 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, therefore that is very easily handled. And so what's the difference between a project studio and a commercial studio? Basically, a commercial studio is accessible to all comers at an hourly or day-to-day rate. Get a booking, perform 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 perhaps a composer working on a Tv soundtrack. Commercial bookings aren't welcome in a project studio simply because a) they're taking up studio time that the owner would most likely 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 most likely go through the roof.
What people do in their project studios is of course literally their own business! But I have identified at least 5 distinct categories of project studio. Have a look at what you can obtain.