Excel VBA – UserInterfaceOnly

What is the difference between the two procedures below?

Sub protectOneSheet()
    
    Worksheets(1).Protect
    Worksheets(1).Range("A1").Value = "Kent Lau"
    
End Sub
Sub ProtectSecondSheet()
    ' Using UserInterfaceOnly
    Worksheets(2).Protect Password:="1234", UserInterfaceOnly:=True
    Worksheets(2).Range("A1").Value = "Kent Lau"
    
End Sub