Anything can be intimidating when you first start out. Firearms are no different… there are as many kinds of guns as cars and if you are not fluent in the nomenclature it's easy to get lost at first. It’s not that hard once you learn the basic parts, as many of the parts are the same from firearm to firearm.
Basically, all pistols have a handle or grip for you to hold onto. There is a trigger of some sort to initiate the shooting sequence. The bullet comes from someplace inside [chamber] and goes out a barrel. Sights of various types are used to aim the firearm. Those are the basics… we can get into the weeds on safeties, de-cockers, action levers, and all kinds of extra parts and wee bits, but we won't for now.
The cartridge is the whole package; a bullet is really only the part that leaves out the barrel. The cartridge contains a primer, propellant, usually in the form of gunpowder, and a bullet. When the primer is struck, it makes a spark that ignites the propellant and the small-contained rapid expansion of gasses (explosion) causes pressure to increase until the bullet follows the path of least resistance out the barrel. As its traveling out the barrel, the lands and grooves (spirals cut into the barrel) make it spin and stabilize its flight.
There you have most of the major parts described.
The cartridge, this whole thing is the cartridge. The bullet is only the copper or lead front part and the primer is this copper colored or silver colored part in the center
We will follow up with more parts diagrammed out for a revolver as well as add in some more of the smaller details but for now, the main parts of the firearm should get you started.
Among the best things, you can do if you wish to be better with firearms is practice, that practice does not always mean a trip to the range. The best thing you can do is proper training, on your own or with an instructor. Train a little, a lot. In other words, train in small batches as often as you can.
You can get more detailed information concerning nomenclature and a better understanding of you pistol in the CCW or Pistol-1 class at Raven One-Five for Southern Arizona or at RATH-Defense for Northern Arizona