difference between ! and . character in the syntax of the VBA identifieer

Hi there,
Greetings from Shank. Am new to the forum.

I am in the process of developing a VBA app. The thing is I don't know the difference between the following vb statements. They all behave the same way (i.e copy the contents the Left Text Box to the Right one. Can you tell me what the "!" exclamation mark does when compared to "." dot character. Can I use them Interchangeably.
'Userform1.bas
---------------
Private Sub CommandButton1_Click()

Me.TextBox2 = Me.TextBox1
Me!TextBox4 = Me!TextBox3
form.TextBox6 = form.TextBox5
form!TextBox8 = form!TextBox7


End Sub

Module1.bas
--------------`
Sub displayform()
Dim frm As New UserForm1
frm.Show

Unload frm
Set frm = Nothing

End Sub

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