Your scope of practice varies with the state that you live in. In my state, Tennessee, LPNs can start IVs and give medications, with the exception of a few specific medications. While the track to becoming an LPN is the shortest, your opportunities are also limited. Typically, this takes approximately two years to achieve. Nurses who go through a RN program receive either a certificate or an Associate's Degree.
Registered nurses can work in many areas and have a wide range of privileges.
RNs are the most flexible when it comes to areas in which you can work. Another option is to complete a four-year program in nursing which gives you a bachelor's Degree in Nursing in addition to an RN license. Which path you decide on depends on your short and long term goals. If you eventually want to enter management, education, or advanced practice, then you should definitely go for a Bachelor's degree from the beginning. This will save you in the long run.