Since Samsung announced the Galaxy S4 the processor is a hot item. Samsung needed to use 2 kind of processors because of the huge amount of Galaxy S4 devices needed for the launch. Samsung choose for their own Exynos 5 Octa (GT-I9500) and for the Snapdragon 600 (GT-I9505). According to JK Shin president of Samsung Mobile it doesn't matter which processor you use. Ok yes JK Shin is right, but the Exynos 5 Octa is a little bit better than the Snapdragon variant. The only good thing is people will not notice this.
If you want to know which processor your country will get check out this link
