This is a great question and one which generated a lot of debate on social media. Different providers of the traditional Emergency Services Officer (ESO) seem to be using different acronyms for different adverts.
In short here it is:
ESO - Emergency Services Officer
MESO - Medical Emergency Services Officer
PESO - Paramedic Emergency Services Officer
On some sites there ESO role encompasses Emergency Management, Preparedness & Response, Rescue & Medical. For these roles you are required to have Certificate IV Healthcare (Ambulance) (HLT41120), Certificate III Emergency Response and Rescue (RII30719) & Collect specimens for drugs of abuse testing (HLTPAT005). This is the more traditional ESO role - a hybrid Fire Fighter, Medic role.
On other sites the ESO role is primarily Emergency Management & Rescue while there are additional MESOs who are more medically focused. The MESOs generally have Certificate III Emergency Response and Rescue (RII30719) & Collect specimens for drugs of abuse testing (HLTPAT005), but instead of the Certificate IV Healthcare (Ambulance) they will have a Diploma or Degree in Paramedicine or Nursing and are AHPRA registered. MESOs and ESOs work together in Emergency Services.
More recently the term PESO has been used - Paramedic Emergency Services Officer - replace the Certificate IV Healthcare (Ambulance) (HLT41120) with a Diploma or Degree in Paramedicine & include AHPRA registration.
Depending on the mining company the rates for ESO / MESO / PESO can vary however generally MESO / PESO gets a slightly higher rate per hour than the ESO. On some sites the pay is the same.
Pay is also variable on other factors like experience and qualifications.
Who knows what will be next SESO - Safety ESO?