Difference between FLAC and MP3?

Hi
I'm buying a pair of Beats Pro by Dre tomorrow and i want to make sure i have the best sounding music to make my audio sound AWESOME! So i've read that flac sounds a lot better than mp3 so i've downloaded (or bought) an flac file and i put it on my iphone and used a free app to play the flac file.
Okay but thing is, i can't really tell the difference between the regular mp3 file on the itunes app conpared to the flac file. So I'm just wondering if its worth buying flac files just to have even better music with my Beats on my iphone?

Wow. Where to begin.

FLAC is a better process, may take more space than an MP3, and is truer to the original than an MP3 file. BUT, if you can't tell the difference, then it comes down to whether FLAC is the same price and you have the space to store the larger files.

Some of my players won't yet play FLAC files. Personally, I just get 256 or 320 MP3's.

I do all mp3 on my ipod all the time just so all my formats are the same (I always do 256, good trade off in sound vs space). AAC is good to but since I started with MP3 I keep all the same.