Not quite! There are two paths to becoming a Registered Nurse. At the end of both courses of study you would take the exact same exam to become a nurse: the NCLEX-RN. The choice for most people is based on their financial resources, family situation, etc.
1. Bachelors of Science in Nursing (BSN)
A BSN is a four year degree. The first two years are prerequisites (classes that you must take in order to APPLY for nursing school.) Most people take these prerequisites at their local community college, but I said earlier, you could probably get quite a few done in high school. After you finish your prerequisites you can then apply to nursing school at a university. If you are accepted, you will then have another two years of nursing-specific classes.
2. Associate's Degree (ADN)
An ADN is a two-year degree and is usually done at a community college. For most of the ADN programs here in Texas, there are 1-2 semesters of prerequisites. Then you may apply for an ADN program through your local community college. If you are accepted, you will then take two years of nursing-specific classes.
Both ADN and BSN offer the same license (RN) and usually around the same salary when you become a nurse. There is a huge inflammatory debate about which is a "better" education, and you can search about it on old AllNurses threads. My opinion is that a RN is a RN, no matter the degree, the differences are in the job prospects not the nursing skill. The ADN route is a much cheaper option, since community colleges are really reasonably priced and they will allow you to become an RN a lot faster.
However, as I understand, you have a much better chance of becoming a manager or having a leadership role if you have a BSN, and it seems like the nursing profession is trending toward making BSN the norm. Plus, if you want to go to graduate school one day to become an Advanced Practice Nurse (like a Nurse Practitioner or Nurse Anesthetist) you must get your BSN to proceed with your studies. Since you're young, I'd really suggest the BSN route, because it will allow you more choices in the future. Plus, going back to school only gets harder as you age and have more responsibilities.