What is the difference between a Registered Nurse and a Regular Nurse?

There is no "regular" nurse. A nurse is an RN - registered nurse. They go to school for that, and some have a BS in Nursing as well.

There is LPN - Licensed Practical Nurse. They also go to school to get a license to do some nursing, mostly the hands on daily patient care.

Level of education.

There are zillions of other "certified" nurses besides registered nurses. RN's are the most popular of the nurse categories; other certified nurses such as licensed practical nurses (LPNs), nursing attendants (NAs), patient care techs (PCTs), etc. generally require less education than RNs and provide for different care. RNs have more responsibility and autonomy than other nurses do (such as administering medications and performing certain procedures). But the responsibilities and duties of each nurse - RN or otherwise - varies slightly on institution to institution that decides what nurses will be responsible for.
To be an RN, you need a minimum of 2 years of undergrad plus an exam (associate degree in nursing), or a diploma program given by a hospital (which is very hard/rare to find nowadays - they used to be very popular way back when), plus an exam. Other certified nurses usually take some certification classes and pass an exam to practice, which can happen in a matter of a few months to a few years.

about a years worth of study in most states

I am currently an LPN going to school for my RN and there are some big differences! LPN's do a lot of the hands on care but less involvement in physical assessments, IV medications, blood administration. RN's are responsible for more in depth care and doctor invovement and they are also invoved in more of a critical thinking aspect of patient care. They also have more responsibility and legal liability in certain situations than an LPN does.