9mm Pistol Rounds - Is there a difference?

Picture it. You are a first time pistol or Pistol-Caliber Carbine owner that uses 9mm as its ammunition. But you have a few questions that many have asked when choosing 9mm ammunition.
-What are the different 9mm measurements? Which form do I use and how do I tell which 9mm is the correct one to use?
-Why are the prices so very different for the various types of 9mm ammunition?
-Does my firearm perform in a different manner when ammunition is loaded than when it doesn't? If it does, what's a safe way to learn my firearm safely until I make it to the range?
-What is "self-defense" ammunition? How is that different from anything else?
These questions are answered here in this video, and describes the various type of 9mm ammunition, what to look for when it comes to what fits your weapon, and what to use for practice to know your firearm better.