Avrodamo,
The difference between the CPL and ATPL....
Well, if you want to work for the airlines like Artificial Horizon said you'll need an ATPL to get a command.
It all first starts with the PPL if you're going modular, then enough hours to sit the CPL or ATPL theory exams. The difference being for instructors and airlines. If your ultimate goal is the airlines which most is, you are better off doing the ATPL theory exams. However, there are no schools offering the JAR CPL theory anyway (at the present time).
Once you have done the theory exams you can progress and do the CPL course then the multi IR. You will then have a frozen ATPL, CPL/IR. Once you get to 1500 hours you can unfreeze the licence. However, you can happily work for an airline with your CPL/IR (if you can get a job). You can add Performace A too plus either an instructors rating or an MCC.
I hope that the information has been helpful, good luck and I hope you get a job soon after your training.
Homer
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Duff, Duff, that Wonderful stuff. Ummmmm Doughnuts