Thinking about going to the UK and would like some help with the different terms. I understand PRHO and SHO and Specialist Registrar but could someone please define the following terms and maybe put all of the positions in a hierarchy for me? thanks in advance.

Consultant
Associate Specialist
Staff grade and Trust grade
Clinical Assistant/Part-time medical officer
Hospital Practitioner
Senior Registrar
Registrar
House Officer
Non-graded/other

OK, here you go...

Consultant
The Boss. God.

Associate Specialist
Not 100% on this term but I think it's consultant level also but without certain duties/responsibilities.

Staff grade and Trust grade
Staff grade is a non-training grade at SHO or Reg level. Not sure what Trust grade is...it's peculiar to the NHS though...

Clinical Assistant/Part-time medical officer
These are usually GPs working in hospitals. Not at the same level as consultants though.

Hospital Practitioner
Not sure! Probably the same as Clinical Assistant...

Senior Registrar
Registrar
Reg and Senior Reg mean pretty much the main thing now. Specialist Reg (SpR) is the new specialist training grade after Reg/Senior Reg.

House Officer
Intern, PRHO, Junior House Officer

Non-graded/other
Collective title for all types of non-training grades.

Hope that helps!