Licensed Practical Nurse (LPN) is a licensed nurse with a more limited scope of practice, in most situations, they report to a Registered Nurse (RN).
Education to become an LPN is shorter. In my state, after pre-reqs are complete, a diploma to take the LPN exam can be obtained after 2 semesters at a community college (about 1 year).
RN has more than one avenue to obtain. BSN is a Bachelor's in Science in Nursing, so it is at least a 4 year degree. ADN is Associate's Degrees in Nursing, so essentially a 2 year degree from a community college. BSN and ADN take the same licensing exam to obtain an RN, which is the license to practice as a nurse. There are also some states that have Diploma programs to obtain an RN, I don't believe my state has these any longer and I don't really know how they work...about 3 years, I think.
All schools have their own requirements and pre-reqs that are required before actually beginning in the nursing program
so the time to complete could vary based on the school and program you choose. There is a lot of talk about the eventual entry level requirement to practice as an RN is the BSN. I am an ADN with a BS in another field and didn't have a problem finding a good job as an RN but I think different areas of the country may be more difficult.
Best of luck to you. It can all be very confusing in the beginning.