In which APN track do you learn the most?

You are mixing up different RN roles, with various APRN roles. CNS, NP and CRNA.

CNS is a non-prescribing role. I am not even sure why it still exists, although God bless the folks who do it. They have gotten an expensive Master's degree, but probably no raise. They usually cannot bill insurance, but there are some exceptions.

CRNA is very focused on that field only, and absolutely could not work as FNPs or any other NP role.

From your question, I glean you are probably interested in the Acute Care NP role.

Keep researching.

First of all, there is no APRN role that encompasses all other roles. There is no APRN role that learns, or can do, *more* than any other. Similarly to physician practice, NPs choose specialties to cover certain areas of medical practice. Your job description is based on what specialty of medicine in which you practice.

Second, I'll quickly try to dispel a myth among many nurses that FNPs can do the most or see the most types of patients. While it is true they are able to see peds, adults and certain OB/Gyn issues they do not have nearly the same depth of training that PNPs, AG/ACNPs, PMHNPs or WHNP/CNMs have in those respective specialties. FNPs gain a wider knowledge base than the other specialties, however, the other specialties gain a much deeper knowledge base in their populations and specialties. An FNP must split their clinical hours between peds, women's health, and primary care, so they receive considerably less hours in each of those areas than do the other specialty track NPs. Further, they receive zero hours in acute care medicine and often times psychiatric medicine.

If you judge "doing the most" by what track does the most procedure type work, then an acute care track (adult or peds) probably does the most hands on procedures. Things like central lines, swans, a-lines, intubating, chest tubes, etc. Although outpatient providers like FNP, PNP, WHNP can do many hands on, office based procedures such as I&D, simple lac repairs or excisions.

Your task, prior to choosing a NP track, is to decide what area of, or type of medicine you want to practice, then choose the NP specialty track that will best prepare you to work in that area.

As an Acute Care Nurse Practitioner, I'm sure that they should be able to do anything that a CCU RN, ER RN, or ICU RN, is able to do right? Because they would have had experience in those roles, or at least studied those roles in Nurse Practitioner school right?

NPs will not be doing what an RN does in any given specialty. They are different roles.

Can an NP do what an ICU/ER/CCU RN does? Sure...

Will an NP be doing what an ICU/ER/CCU RN does? No...

So for example, all factors considered equal, can a person with CRNA training do anything that a person with FNP training can do?

You really need to explore the different graduate level training options available within nursing. A CRNA will do essentially nothing than an FNP does, and, similarly, and FNP will not be doing anything that a CRNA does. ACNP and CRNA are a little more similar in certain tasks such as intubating, placing lines, etc. But each APRN is designed to practice in a different area of medicine. FNP, CRNA, PNP, CNM, ACNP, WHNP, ACNP, CNS... they all train in different specialties and therefore their practice is different.