A Registered Nurse needs at the very least an Associates of Science Degree. It is becoming more and more usual to see most employers asking for a Bachelors of Science degree however. There are bridge programs that will assist you in obtaining your BSN once you have obtained your ASN. RN schooling can be anywhere between 2-4 years depending on part/full-time status.
Now a Licensed Practical Nurse is still a nurse. They have to test just like a RN does. Schooling is generally the same except for a few courses .