The short answer is that you can use student loans for living expenses. Joe provides a nice taxonomy of loans. I would just add that some loans are not only guaranteed, but also subsidized. Essentially the Government buys down the rate of the loan.
The mechanics are that a financial aid package might consist of grants, work study (job), subsidized, and guaranteed loans. One can turn down one or more of the elements of the package. All will be limited in some form.
The work study will have a maximum number of hours and generally has low pay. Many find better deals working in the businesses surrounding the college or starting their own services type business. The grants rarely cover the full cost of tuition and books. The loans will both be limited in amount. It mainly depends on what you qualify for, and generally speaking the lower the income the more aid one qualifies for.
Now some students use all their grant, all their loan money and buy things that are not necessary. For example are you going to live in the $450/month dorm, or the new fancy apartments that are running $800/month? Are you going to use the student loan money to buy a car? Will it be a new BMW or a 8 year old Camary?
I see this first hand as I live near a large university. The pubs are filled with college students, not working, but drinking and eating every night. Many of them drive very fancy cars.
The most onerous example of this is students at the military academies. Attendees have their books and tuition completely paid for. They also receive a stipend, and more money can be earned over the summer. They also all qualify for a 35K student loan in their junior year. Just about every kid, takes this loan. Most of those use the money to buy a car. I know a young lady who did exactly that, and so did many of her friends.
So kids with a starting pay of 45K also start life with a 35K. Buying a nice car in the military is especially silly as they cannot drive it while deployed and they are very likely to be deployed. At least, however, they are guaranteed a starting job with a nice starting pay, and upward potential.
College kids who behave similarly might not have it as good. Will they even find work? Will the job have the ability to move up? How much security is in the job? One might say that this does not apply to engineers and such, but I am working with a fellow with a computer science degree who cannot find a job and has not worked in the past 6 months. This even though the market is super hot right now for computer engineers.
So, in a word, be very careful what you borrow.