They are just two variations of the same basic design. Either one should perform very well.
Oh and i also saw it said it can support another normal 120mm mm fan on it so how much cooler will it be?
612 comes with two fans running at 600-2000 rpm 612s comes with one fan in which maximizes at 1300rpm. Also comes with an adapter to lower the speed to 900rpm to be more silent.
So the 612s will make the CPU warmer than the 612 normal edition?
Looking at the specs, the 612 will push more air than the 612s. It all depends on placements of the cpu coolers' fans. As long as the fans is blowing the air towards the exhaust fan at the rear of the case your system should have no problems.