Are n scale model train bigger then g scale?

No. There are many scales of model trains which include from the smallest "Z-scale" (1:220), "N-scale" (1:160), "TT-scale" (1:120), "HO-scale" (1:87.1), "OO-scale" (1:76.2), "S-scale" (1:64), "S-scale" (1:64), "O-scale" (1:48), "1-scale" (1:32) and the largest, "G-scale" (1:22.5).