Well, I am not quite sure what your getting at but here it goes. When your 16 you can solo or known as having a student pilot certificate. At 17 you can get your Private Pilot certificate meaning you can carry PAX. If you want to be a commercial pilot you need to be 18 for that. Also, they are certificates, not licenses, had a FAA inspector bash me on that when took my CFI. Though I do admit from time to time I still call it a license. Anything added on to that certificate (instrument, Sea plane, Multi engine) are called add on ratings. One more thing it is by no means anything like a drivers license it is much more responsiblity than driving a car. If you want to be an airline pilot good luck. It takes a lot of hard work and dedication.