CHN is basically the umbrella that PHN and several others fall under. CHNs are all the nurses that work in a public setting, ie, not in a hospital or clinic. A public health nurse is what you typically think of when you think of CHNs... they do immunization clinics, visit new moms, visit schools for health programs etc. Also falling under theCHN umbrella you have things like home health nurses, parish nurses, street nurses, those involved in public health policy and promotion campaigns, etc. HTH!