RE: I am seeing better results from dumbell flatbench?
Anatomical differences from person to person for one. Your benching form also figures in. While I value bench press as an overall upper body size/strength builder, bench does not build a great chest for everyone. I have seen many trainers with a strong bench and relatively flat chests, big front delts and large triceps (myself included). I find that dumbell movements help remove some of the assisting muscles' influence.