The J-20 is a twin engine fighter compared to the F-35 single engine fighter so the J-20 will outfly the F-35 in terms of speed and altitude. It is more fair to compare the J-20 vs the U.S. F-22.
yes this point was obliquely made in the article, with some question as to how to intended use of the J-20. Nevertheless, the encounter was between J-20 and the F-35
