The licence you hold determines whether you have to pay for your flying (PPL) or can get paid to do it (CPL, ATPL).
The ratings that are attached to the licence determine what you can fly.
I suppose in theory there is no reason why you can't attach a 747 type rating to a PPL, BUT, as a 747 has jet propulsion, is pressurised, has hydraulic systems, incorporates an IR element in the type rating skills test, requires complex flight planning skills, is in performance category A, etc, by the time you have done technical exams to give you privileges to cover the subjects (and others) above, it might well have been quicker and cheaper to have done the ATPL theory subjects, and the CPL/ATPL flight training, and got yourself a CPL/frozen ATPL.