I’ve looked it up, but all of them essentially sound like the same thing to me. I’m aware that there’s probably some nuance, so that’s what I’m posting it here for.
Neuroscientist: a science person that studies nerves and brain in general.
Neurologist: a neuroscientist who is also a doctor and studies how your nerves affect your body. Unlike some other neuroscientists he doesn’t care how your brain activity links to your movie preferences, but he can check if your nausea comes from some nerve pathology.
Neuropsichiatrist: more brain- and behavior-oriented than the neurologist, he studies psychic illnesses specifically and how they are linked to the processes in the brain. He can tell you that your seizures and hallucinations are caused by your brain lobes being weirdly formed.
Neurosurgeon: a guy with a scalpel who will remove your brain tumor or sew your spine after you fracture it. Basically, a surgeon who specializes in nerve tissue.
It gets even more nuanced for neurologists: neuromuscular, headache, sleep disorder etc etc
Using analogy in another field:
A neuroscientist is like a physiotherapist. They have trained in that field specifically, and are usually highly skilled, but not medical doctors.
Neurologists and neurosurgeons are medical doctors, like sports physicians and orthopaedic surgeons.
Neurosurgeons are like orthopaedic surgeons. They cut. They work out if surgery is needed and do it if so. If not, they usually don’t have an ongoing management role.
Neurologists are like sports physicians. They don’t do surgery, but do the other care that you doesn’t need surgery. Think Parkinsons, multiple sclerosis, epilepsy (without a surgical cure) etc.
Neurologist gives you drugs. Neurosurgeon cuts you open. Neuroscientist studies the brain. Neuropsychiatrist probably gives you therapy and drugs. Encephalology is the study of head related stuff, including stuff that’s not brain.