Red and Green days?

Was just wondering if anyone could help me understand the red and green days? I've just started slimming world online and have just been doing extra easy days up to now. Would anyone say that the red and green days make a difference or if they are better than just extra easy? Thank you

Please view my post to a similar question http://www.minimins.com/slimming-world/347678-ee-red-green-days.html#post7626231

Also, please check out this sticky http://www.minimins.com/slimming-wo...orld-works-advice-newbies-updated-2014-a.html