They're fairly similar, both made in the same factory in Russia. Not sure on the excact differences, possibly a different grind on the blade, different finish maybe, St Petersburg Products aren't clear on what the differences are.
They're both really good, some people say yellow are that bit sharper, some complain of an initial roughness, whereas some like the smoothness of the green, I just really like both blades to be honest.
There is another 7 o'clock green blade which is labelled "Permasharp" as opposed to the Russian "Super Stainless" that you have... the former are made at the plant in India and are not quite so good.