Of course there is no difference at move 6 unless one lad in the 1.c4 game
does not realise he playing a Philidor or visa-versa and gets his theory mixed up..
In the exchange variation of the Phildor White gets a reasonable position
with 4.Qxd4 then pin the c6 Knight with Bb5. That is what Morphy played.
He also played 4.Bc4 instead of taking back on d4 this is called the Morphy Gambit.