There are two piers which are on the same slip of water but are opposite one another so are accessed by different roads, thus the different name in piers. If you tell your cabbie which line you are sailing they will get you to the correct pier. They know which ship is where. Or, usually the pier name is printed on your ticket or port information.
If you are going directly from the airport it will take you 20-30 minutes from the time you enter the taxi stand til they drop you off at the pier. It isn't far at all. The pier staff is very efficient and it is one of our favorite places from which to sail. If you have time, I would highly recommend you fly in the day before. It takes so much stress off your plans, you can enjoy a nice evening listening to the waves crash on the beach, watch your first tropical sunrise (or sleep in and rest up!) they mosey on over to the ship at your leisure.