Bad credit is much worse
You ask two questions.
Considering your age, you probably don’t have credit history yet. Do you have a credit card on your name? Did your parents ever have you co-sign on their credit card?
If not, than you probably have no credit history. Your chances of getting a car loan is probably zero, unless your parents take the loan with you.
If you’re not sure pull put your credit report and find out for sure.
You need to build a good credit history if you ever want to get approved for a car loan. You can find a lot of information about it in this site.
You need to get a small secured loan, and a secured credit card. They are easy to get because they are secured. After 6 month you will have a fair credit score, and after a year who may try to get the car loan.
As far as bad credit vs. no credit:
The consequences are the same because as it goes to getting loans – you can’t get any loan with both.
If you have no credit history – it may take you a year or two to establish good credit. If on the other hand you have bad credit – your situation is MUCH WORSE because it means that you have negative items on your credit report.
Negative items remain for a long time on your report (most remain for 7 years), and until they go away they will lower your credit score.
Hope this helps
Tracy