Ok let me explain
CAA staff flight examiner- is an employee of the UK CAA. This TRE is approved normally on all types (a blanket approval), and they are the ones that carry out Observed Flight Tests. Put it this way, to get a IR in the UK you need to be tested/observed by a UK CAA staff examiner at some point.
CAA TRE- Any UK approved TRE
Fight Saftey TRE's in USA are approved to do LPC's. These examiners are approved under a blanket company approval as they are not JAR licence holders themselves. The UK CAA gives approval to Flight Satey as a TRTO, and these FAA examiners are given "approvals"-not licences to do LPC's under this TRTO approval. A FSI TRE cannot complete a UK JAR ATPL (A) skills test for the purpose of upgrading from CPL/IR to ATPL.