I can tell you the difference but it's gonna coast ya! (get it? "Coast," ya? Ha! I kill me!)

I've owned a few fixed gear and single speed bikes, enjoyed them a while, currently have none. I did a century on a fixed gear once, just to see if I could. I found descending on a fixie more tiring than climbing, personally-guess it's easier for me to honk uphill in a low cadence than spin a mad cadence going downhill...