Is a dual Channel CORSAIR VENGEANCE DDR3 4GB-1600 of Ram, worth more in performance than a Single Channel Kingston DDR3 6GB 1333BUS??
Dual channel RAM is designed to have 2 sticks that are compatible with each other, so that when you use them, you can put one stick in each channel of your RAM slots if you have dual channel memory controller (most modern computers).
I'm not sure what is the single channel kingston ddr3 6GB. I have never heard of a single stick with 6GB of total RAM. BUT, single channel is usually just 1 stick.
For the same speed, your bandwidth of dual channel is single channel x2. Therefore, dual is faster (though you have to run programs that are sensitive to memory bandwidth to notice).