turtle understanding the window code example

Example 1: create a window turtle python

import turtle

# Create the window
wn = turtle.Screen()
wn.setup(800, 600) # Dimensions
wn.bgcolor("black") # Background color
wn.title("Window") # Title

# Main loop
while True:
  window.update() # Update window

Example 2: turtle with python

import turtle
#creating a square with turtle
t = turtle.Turtle()
t.forward(100)
t.color('blue')
t.right(90)
t.forward(100)
t.right(90)
t.forward(100)
t.right(90)
t.forward(100)