Hi, here is the link to the LACE model which explains it all! On page 10 of the document is a diagram of the model.
There are four groups of Advanced Practice RN's (APRNs; but I am also seeing APNP a lot for advanced practice nurse prescriber): nurse practitioners, clinical nurse specialists, nurse midwives, and CRNA (anesthetists); then the population foci, such as adult/gero or peds; then subspecialties.
So, based on this model, in a few months (assuming I graduate) I'll be an adult-gero CNS with a diabetes focus.
There are also MSN prepared nurses who are not APRNs such as nurse educators, business/management focused, or CNL.
There certainly is an alphabet soup going on in our profession.
We do need to be able to speak to this topic and questions about the initials and scope.
I hope this helps.