There are several different types of servers that you can make,for example BungeeCord or Spigot.

Servers are made to allow you to play with other players(multiplayer) but there are different types depending on what server you want.For example Bungeecord is used to connect multiple spigot servers together so that you can have separate servers on one,lets call it a mega server.This mega server has spigot servers connected to it and you can travel across all of them.The only job BungeeCord does for you is that it binds all those spigot servers together.A spigot server is a better version of "craftbukkit"(we wont be talking about it because its pretty much outdated and nowadays spigot is used)and is used because it allows you to have "plugins" such as the famous one called "worldedit" that allows you to do this more quicker and easily in a world.Pretty much thats why you would get spigot.Why plugins ? Well plugins change the way minecraft works BUT that doesnt mean it changes the whole of minecraft but part of it.For example a plugin called "worldedit" as mentioned before can let you edit a regular minecraft world and let you do things more faster and easily but it wont change anything else such as lets say the objects in minecraft.It will only do what it has said and it is interesting once you meet it.Plugins make minecraft more complicated but also fun.Some people prefer minecraft as it as and other want to modify it and thats just life,everyone wont have the same opinion but have the choice to change :).