Pi not loading certain distributions from SD

Hey all,

I'm just getting into Pi and what it can do. I decided I'd start by looking at RetroPie and RasPlex. However, no matter how I format the card, only a certain image of Noobs will boot. If I format the card and just copy over the boot files into the root folder, it will not boot. I'm so confused as to why this happens.

Any ideas?

Thanks...