I mean it wasn't difficult to wikipedia how many goals Johnson scored last season and how many goals Nico Williams scored last season..
The reasoning of 'It's because he's better' is hardly backing up the point of why Nico Williams is a 'level' above Johnson...? When the most basic of stat proves that he isn't.
Brennan Johnson coring more goals than Williams proves nothing other than he scored more goals.
Quick glance at other stats shows that Williams is in a much higher percentile for chance creation, makes far more crosses, has a better cross success rate, assists every 600 minutes or so vs every 990 minutes, is in the 99th percentile for successful dribbles (!!) vs Johnson in 75th percentile, and weirdly enough also looks much better defensively .. if that's your thing.
None of which even means he's better. I haven't watched enough of him to say. But "Johnson scored more goals" isn't exactly compelling when it looks like Williams is being used as a more traditional ball carrier/creative wide player, which is generally what it seems like Ange wants.