Can drop down menus make different tables visible?

By dropdown menu, do you mean a content control dropdown box in the document?  If so then proceed as follows.

1.  Add the dropdown and define it's list members (here I've used Table A, Table B ...).

2.  Create BuildingBlocks of each of the three tables.  Use the AutoText gallery in the attached template.  Name the building blocks "Table A, Table B, ...

3.  Add the following code to the ThisDocument module of the template.

4.  Add a bookmark "bmTable" where the table needs to appear.

Private Sub Document_ContentControlOnExit(ByVal CC As ContentControl, Cancel As Boolean)
Select Case CC.Title
  Case "Table"
    Select Case CC.Range.Text
      Case "A"
        UpdateBookmark "bmTable", "Table A"
      Case "B"
        UpdateBookmark "bmTable", "Table B"
      Case "C"
        UpdateBookmark "bmTable", "Table C"
   End Select
 End Select
End Sub

Sub UpdateBookmark(BmkNm As String, Optional strATName As String)
Dim BmkRng As Range
With ActiveDocument
  If .Bookmarks.Exists(BmkNm) Then
    Set BmkRng = .Bookmarks(BmkNm).Range
    If strATName <> vbNullString Then
      On Error Resume Next
      BmkRng.Tables(1).Delete
      On Error GoTo 0
      Set BmkRng = ActiveDocument.AttachedTemplate.AutoTextEntries(strATName).Insert(Where:=BmkRng)
    Else
      BmkRng.Text = vbNullString
    End If
    .Bookmarks.Add BmkNm, BmkRng
  End If
End With
Set BmkRng = Nothing
End Sub

When the user selects the table from the CC and exist, the appropriate table will appear at the bookmark.

I certainly don't mean to sound pompous or arrogant, but I really don't know what else I can do to make it clearer.  Maybe this will help:  See: http://gregmaxey.mvps.org/word_tip_pages/installing_employing_macros.html for instructions to employ the VBA code provided above.

AttachedTemplate is the template attached to the document. If your document began life as a new blank document, then that template is Normal.  If it began life from some other template (e.g., My Letterhead Template, then that template is most likely the attached template.

When you create and save the buildingblock, save it in the name of the attached template, not BuildingBlocks.

You're welcome.  I remember the time when I likewise struggled with macros.  It is just hard to think like that now :-(