First, ER nurses work in the main entry point of a hospital or major health care facility while ICU nurses work on a separate floor that is generally far quieter and calmer than the bustling emergency room … I have been both....a ICU nurse and an ER nurse. The differences in working environment for an ICU vs an ER nurse. ER nurses are the first line of medical professionals you … What is an ER Nurse? Head to toe assessment are done on … First remember in the ICU the enviroment is completely different and a more controlled kind of chaos. The ICU is often the next step for patients who’ve made a (justified) trip to the emergency room after the ER team determines they’ve stabilized enough to move on. Just like ICU nurses, ER nurses need to be equipped with a quick critical thinking, decisive action PLUS a strong stomach. One major difference in this unit for nurses is the nurse to patient ratio—typically ICU units strive for one to two patients per nurse.