Differences between resistors?

[garrettwrhodes]

I'm going through a build and I have a question. I am doing a NBv3 with Blue/RoyalBlue/White. For the blue LED's I don't know what the difference between this .5ohm 3w (http://www.thecustomsabershop.com/5ohm-3w-resistor-P1050.aspx) vs this .47ohm .5w (http://www.thecustomsabershop.com/47ohm-5w-resistor-P947.aspx) resistor. Does it matter? Will one yield better performance?

Thanks,
-Garrett

[NanoRex]

Size. One is huge, one is not. More power dissipation = bigger resistor.