What is casing the difference in behavior in the following 2 grids?

Question

• Can someone help me understand in a low level language of what is happening in the following python code? Why in the first grid A gets assign to every row for 7 col while grid2 only to (6, 7) coordinates?

   w, h = 10, 10
   grid1 = [[0 for i in range(h)]] * w
   grid2 = [[0 for x in range(w)] for y in range(h)] 
  
   grid1[6, 7] = 'A'
   """
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 A 0 0 
   """
  
  
   grid2[6, 7] = 'B'
   """
   0 0 0 0 0 0 0 0 0 0 
   0 0 0 0 0 0 0 0 0 0 
   0 0 0 0 0 0 0 0 0 0 
   0 0 0 0 0 0 0 0 0 0 
   0 0 0 0 0 0 0 0 0 0 
   0 0 0 0 0 0 0 0 0 0 
   0 0 0 0 0 0 0 A 0 0 
   0 0 0 0 0 0 0 0 0 0 
   0 0 0 0 0 0 0 0 0 0 
   0 0 0 0 0 0 0 0 0 0 
   """