The differences between Judge and Riley are huge...
First, Judge has 80 grade power, whereas Riley has closer to 60 grade power. While Riley had a good 94.1 mph average exit velocity, Judge blew him away with a value of 100.2 in 2016. Comparing Riley's power to Judge's is completely laughable. Judge produces the most valuable contact in all of MLB.
Second, Riley's O-Swing% in 2019 was 41.3%, good for 22nd worst out of 320 hitters with 250+ Pas. Judges O-Swing% in 2016 was 33.6%, which would be somewhere in the middle of the pack, and it has since improved to ~25% in subsequent years. Judge's ability to identify bad pitches was far superior to Riley's, even when he was at his worst.
Third, Riley's Z-Contact% of 73.6% in 2019 ranked 3rd worst of those same 320 hitters, meaning Riley struggles greatly to make contact on strikes he decides to swing at. Not being able to make contact on strikes is a pretty big deal for a baseball player. Judges' Z-Contact% has been consistent at around 79% from day 1, and while still bad, better than Riley's...and always has been.
In short, Judge at his worst still hit the ball much harder than Riley, identified strikes much better than Riley, and made more contact than Riley.
The red flags for Riley are right red, and they have been there from the moment he took his first 50 PAs at the MLB level. He is a pure guess hitter, and until he improves upon the metrics I listed, there is no way he will stick at an MLB corner.
Can he improve those metrics? No idea, but I wouldn't bet against it from a talented 22 year old. Even if he can improve those metrics, it would be foolish to pencil him into the lineup for opening day 2020 until he shows positive signs.