What is the concept of ambulance, ambulance and emergency vehicles have what is the difference between

Ambulance, as the name suggests, the ambulance is to rescue the patient's car, ambulance is generally divided into transit type (no emergency medical equipment, does not have the function of first aid, can only be a simple transfer of patients) and monitoring type (defibrillator, electrocardiograms and other emergency medical equipment, can be in the car to rescue the patient), but in some places the emergency vehicle and the equivalent of an ambulance.