In order to understanding the difference between tungsten single‐wire‐array and tungsten nested‐wire‐array Z‐pinches, we have measured the x‐ray power, the temporal‐spatial distributions of x‐ray radiation from each of the two loads. The measurements were performed with 0.1mm spatial and 1 ns temporal resolutions at 2.5‐ and 3.5‐MA currents. The experimental conditions, including wire material, number of wires, wire‐array length, electrode design, and implosion time, remained unchanged from shot to shot. Analysis of the radiation power profiles suggests that the nested‐wire‐array radiate slightly less x‐ray energy in relatively shorter time interval than the single wire‐array, leading to a much greater x‐ray power in nested‐wire‐array implosion. The temporal‐spatial distributions of x‐ray power show that in both cases, plasmas formed by wire‐array ablation radiate not simultaneously along load axis. For nested‐wire‐array Z‐pinch, plasmas near the anode begin to radiate in 2ns later than that near the cath...