Mongoose is quite correct - The 'JAR-compliant' licence is a well-known and long-standing marketing ploy that has absolutely no meaning (or value). It is no more than a licence issued in accordance with ICAO Annex 1 that is, consequently, recognised as valid by every other ICAO member state. In the case of UKFT, mentioned above, it is a FAA PPL, which could be obtained at any other US flight school, probably at much less cost. In fact, it has no more value than a PPL gained in any of the other ICAO member states any of which can be converted to a JAA PPL in exactly the same way.
JAA is an acronym for the Joint Aviation Authorities and JAR for the Joint Aviation Requirements. The terms JAA licence and JAR licence are interchangeable in common parlance although the former is more correct. All a bit pointless as the JAA will cease to exist at the end of this year.