In the UK at least, there's much less stratification than there once was I think.

For example Advanced Nurse Practitioner status grants nurses almost all prescribing rights you'd get as a doctor. They're allowed scheduled drugs (ie stuff that's commonly abused) because a bunch of those are effective painkillers and a key reason to have Advanced Practitioner is that "This patient is in agony, and I know the only thing a doctor would do is give them these stronger drugs, but I'm not allowed to do that on my own" is a stupid situation to put an experienced nurse in, so let's just authorise them to do it.

I believe there are Advanced Practitioner variants for several other healthcare roles including midwife and pharmacist; in some cases you just get limited prescription rights (so you can only give people some specific prescription drugs from a list) but in other cases like Advanced Nurse Practitioner it's the whole thing, if your knowledge and experience tells you that off-label use of a heart medicine is the right way to solve your patient's acute hiccups you can do that just like a doctor could.

To qualify for advanced practice these professionals are doing much of the same work student Doctors do - but just focused to their specific discipline. Lots of Chemistry, learning how to read research literature, and so on. They get a post-graduate degree of some sort, I don't remember the exact title.