Ajuda para entender um codigo de migração de banco de dados

procedure TMainformDialog.pxLoadTables;
var
  Tables:TStringList;
begin
  Tables:=TStringList.Create;
  try
    Database1.GetTableNames(Tables);
    ListBox2.Items.Assign(Tables);
  finally
    Tables.Free;
  end;
end;
 
procedure TMainformDialog.nxLoadTables;
var
  Tables:TStringList;
begin
  Tables:=TStringList.Create;
  try
    nxDatabase1.GetTableNames(Tables);
    ListBox1.Items.Assign(Tables);
  finally
    Tables.Free;
  end;
end;
 
procedure TMainformDialog.FormCreate(Sender: TObject);
begin
  DataBase1.Connected:=True;
  nxDataBase1.AliasPath:=ExtractFilePath(ParamStr(0));
  nxDataBase1.Connected:=True;
  pxLoadTables;
  nxLoadTables;
end;
Top Button (Display PX):
procedure TMainformDialog.Button4Click(Sender: TObject);
begin
  If ListBox2.ItemIndex<0 then ShowMessage(´No Table Selected´) else
  begin
    Table1.Close;
    Table1.TableName:=ListBox2.Items[ListBox2.ItemIndex]+´.DB´;
    if Table1.Exists then Table1.Open else ShowMessage(´Sorry - that is not a Paradox table!´);
  end;