Which one should I watch, FMA or Brotherhood? Is there a difference?

The original anime doesn't follow the manga, while Brotherhood follows the manga. I think you should watch both. The original anime, despite not following the manga completely, is incredibly emotional, though it's also very dark as well. It's amazing in my opinion. Brotherhood is more humorous and less dark, but it's great as well! But yeah, in my opinion, you should watch both. The more Full Metal Alchemist the better, right? <3

I won't watch either because I detest the art style, but I hear Brotherhood follows the manga while Hagaren (FMA) does its own thing.