find mor info here:
http://www.jaa.nl/section1/jarsec1.html
download the PDF for the JAR-FCL 1
look for CPL privileges at JAR-FCL 1.150
and for ATPL privileges at JAR-FCL 1.275
CPL allowing only PIC in single pilot operation and co-pilot in multi pilot aircraft.
ATPL (you get all the privileges)
If thinking to fly a biz-jet once get the ATPL anyway. So you get all done in once - jet aircraft - high performance, RVSM, long range nav etc. study once take examination once. as the difference is only the theory part which should not be that much more expensive than a CPL.