How does the direct gas impingement operation differ from the piston-driven operation?

Both do use the gasses from a fired round of ammunition to begin their cycle of operations however the manner in which that gas is used differs greatly. Direct impingement pushes the gas down a confined tube and push the bolt that is in direct contact with it. This method uses the directed gas to push the bolt, separating the gas tube and gas port so the remaining force can be expelled. Piston driven systems use an actual piston to physically move the bolt. The gas traveling into the gas port pushes against the piston head moving the connected rod rearward to physically move the bolt. Both methods work great, but I fall on the fence here. Each was its place in battle but usually the environment where one shines the other perishes. The grass is always greener on the other side.