When you enter a program you will generally choose a track - Pysch NP, FNP, Acute Care NP etc. Education tends to diverge once you're past the initial classes. My program has Adult, Family and Acute together, but as we're in our first term of clinicals this is our last term together. In the fall we'll split, but we were together for pharmacology, policy, patho, genetics, etc.
You will take the exam for your track when you graduate, from one of the two certifying organizations - AANP or ANCC. Your state will then grant you a license once you've applied.
As you'll see if you peruse the boards, it is highly recommended that you work as an RN for a while to gain knowledge and to determine which area you'd like to pursue. You don't want to spend money getting a second post-master's certificate and taking another board exam if you decide you like another track better.