Hi Angel
Firstly, a CPL is a Commercial Pilot's licence, which qualifies you for command on smaller aircraft - an ATPL (Airline transport Pilot's licence) allows you to be in charge of big ones - to get this you need more flying hours, have to pass more exams and be older.
Countries can issue their own licences which are ICAO-compatible - they are not automatically exchangeable between countries, but some have agreements that allow this - Australia and new Zealand, for example. Others require you just to take a law exam (UAE). Others (e.g. JAA/FAA) don't allow exchanges at all. Canada will accept a current PPC for a type rating (depends on the office!0
Countries that belong to JAA (shortly to become EARSA) can also issue JAA licences, which enable to fly in any JAA country without formality - the licence isn't exchangeable without paperwork, but you can fly in any country on the original JAA licence. However, if you reside in any country for more than 183 days in any year for tax reasons, you have to get it reissued by the relevant state, but this is also for tax reasons.
Phil