CPL is the license you get from basic aviation training. Entitles you to fly in light commercial aviation as commander on aircraft not certified for multicrew operation or as co-pilot in a multicrew environment.
ATPL entitles you to act as commander in a multicrew environment and requires that you have at least 1500 total flight time (along with some other hour requirements).
The normal thing as that you get your CPL together with the ATPL theory and thus get a "frozen ATPL" . Once you are eligble for the ATPL it will become "unfrozen".
Cheers,
Olof