What's the point of using Bukkit instead of Spigot?

I've been hosting private servers for a while now, but it's only about a month ago that I got into bukkit and started learning about plugins. It told me that I needed to update bukkit but when I went to the downloads page, it listed Vanilla, Bukkit, and Spigot. I researched a bit into Spigot and the only thing that I could find was that Spigot runs better than Bukikit.

So that begs the question: Why even use Bukkit in the first place? How come I've never heard of Spigot until now? If I know how to setup a server by myself, are there absolutely any reasons for me to use Bukkit instead? 9apps cartoon hd

 

in my experience Spigot has somehow different monster spawning parameters and I was simply unable to make it work the same as craftbukkit and my mobtrap didn't produce almost any monsters in Spigot. That's the difference I have noticed... but maybe there was some parameter I forgot to change?