Using tkinter in Python. Created a dialog box from tk.Toplevel()

After reading various posts and docs:

    self.resizable(width=False, height=False)
    self.wm_transient(self._mainwin)
    self.transient(self._mainwin)
    self.wait_visibility()
    self.grab_set()
    self.update_idletasks()  # draw
    self.wait_window(self)

Just curious as to what the difference is between wm_transient() and transient()? Do I need both or only one of them?