подобные строки....

var
  line, line2, line3, tmp, tmp2, tmp3: string;
  i1,i2,i3,cnt: Integer;
begin
  cnt:=0;
  i3:=0;
  f1:=TStringList.Create;
  f1.addstrings(memo1.lines);
  f3:=TStringList.Create;
  f3.addstrings(memo2.lines);
      while i3<=f1.Count-1 do
       begin
        For i2:=0 to f3.Count-1 do
          begin
               line := f1.Strings[i3];
               Delete(line, Pos(':', line), Length(line));
               line3 := f3.Strings[i2] ;
               if (line <> line3) then
                begin
                 f1.Delete(i3);
                 cnt:=cnt+1;
                end;
          end;
       i3:=i3+1;
       ProgressBar1.Position := 100 * f1.Count-1 div (i1);
    end;
MemoEnd.Lines.addstrings(f1) ;
end;

procedure TForm1.ProcessMemos;
var
  I: integer;
  SearchLine: string;
begin
  Memo3.Lines.Clear;
  for I:=0 to Memo1.Lines.Count-1 do begin
    SearchLine := StringReplace(Memo1.Lines[I], ':', '', [rfReplaceAll]);
    if Memo2.Lines.IndexOf(SearchLine) > -1 then
      Memo3.Lines.Add(Memo1.Lines[I]);
  end;
end;

  Memo3.Lines.Clear;
  for I:=0 to Memo1.Lines.Count-1 do begin
    Memo1.Lines[I] := SearchLine ;
    tmp := Copy(SearchLine, 1, Pos(':', SearchLine)) ;
    SearchLine := StringReplace(Memo1.Lines[I], ':'+tmp, '', [rfReplaceAll]);
    Memo3.Lines.Add(SearchLine);
    if Memo2.Lines.IndexOf(SearchLine) > -1 then
      MemoEnd.Lines.Add(Memo1.Lines[I]);
  end;

procedure TForm1.ProcessMemos;
var
  I, SeparatorPos: integer;
  SearchLine: string;
begin
  Memo3.Lines.Clear;
  for I:=0 to Memo1.Lines.Count-1 do begin
    SearchLine := Memo1.Lines[I];
    SeparatorPos := Pos(':', SearchLine);
    if SeparatorPos > 0 then
      SearchLine := Copy(SearchLine, 1, SeparatorPos-1);
    if Memo2.Lines.IndexOf(SearchLine) > -1 then
      Memo3.Lines.Add(Memo1.Lines[I]);
  end;
end;

   for b:=1 to Memo2.Lines.Count do
      begin
         s:=copy(memo2.Lines[b-1],1,4)+':'+copy(memo2.Lines[b-1],5,4);
 
         for a:=1 to Memo1.Lines.Count do
            if s=memo1.Lines[a-1] then
               memo3.lines.add(s);
      end;