Oh, now they're rather different players. Should he sign, Aouar will pick up more of the minutes left by Silva. He's better up the park, more adept at finding that space between the opponent's defensive line and midfield line. He also has a sublime touch and excellent peripheral vision which enable him to play on the half-turn, something which very few players can do.
Nothing wrong with a bit of summer greed, so let's have both. ;-)
Think Foden just told you to piss off :)