What are the types of anesthesia?

There is one type of anesthesiologist. But they can do different things, there are Anest. that work exclusively for ER/ICU and other specialty wards, and there are OR Anest. there are also CRNA's (Certified Registered Nurse of Anesthesia) They work under an Anesthesiologist, and pretty much do the same exact job with a little bit less responsibility.