"In the real world," (heh...), there are many version-control systems in use: CVS, SVN, Visual Source-Safe, PerForce ("P4") ... (heh...) "just to name a few."
All of these systems are very different, and, if I may politely say, "all of them have a history." All of them came from "somewhere" and, in their own way, "tried to improve upon 'it.'"
In the very politest and very most sincere way possible, let me gently suggest to you that ... the very nature of your question reveals you to be a 'padewan.' Please go now and spend a few days on the 'official' web sites of, say, (in this order...) "CVS," "git," and "github." Without "rushing to find the answer to just your immediate question as you know it right-now," just poke-around. Kick the tires. Have a look around. Get to know the territory. Try to find out where each of these systems "came from," and what they say they're trying to "improve," and, well, "whatever they might have to say about one another."
Go do that, for a few days, then check back.
Hint: "Am I making fun of you? Absolutely not. 'Go. Do, and question not. Soon, you will know' ..."