I don't see any comparisions.
MVS is a burner with a limited route tree.
Davis is clearly a better route runner with better hands.
With or without Diggs, Gabe Davis has produced.
I think Davis, Watson, and Doubs complement each other well.
You don't see any
Boundary receivers with linear route trees who provide offenses with a vertical dimension. They are both high ADOT players with high variance outcomes. The stats bear it out.
MVS, first three seasons:
38 receptions, 581 yards, 2 touchdowns, 15.3 YPR, 8.0 YPT, 52.1% catch rate
26 receptions, 452 yards, 2 touchdowns, 17.4 YPR, 8.1 YPT, 46.4% catch rate
33 receptions, 690 yards, 6 touchdowns, 20.9 YPR, 11.0 YPT, 52.4% catch rate
Davis, first three seasons:
35 receptions, 599 yards, 7 touchdowns, 17.1 YPR, 9.7 YPT, 56.5% catch rate
35 receptions, 549 yards, 6 touchdowns, 15.7 YPR, 8.7 YPT, 55.6% catch rate
48 receptions, 836 yards, 7 touchdowns, 17.4 YPR, 9.0 YPT, 51.6% catch rate
They're extremely similar. MVS has more pure speed; Davis is better at the LOS and has better hands.
The reason you think they're night and day different is that you watched MVS play and became frustrated with his boom/bust nature as a player, and you haven't had the same experience with Davis. But I guarantee you that Bills fans have.
And if you really believe that Davis is a vastly superior player that MVS, then it should only further support my point in your own mind. If you think Davis is worth 12-15 AAV because he's a tier above MVS at 10 AAV, then he is clearly way more valuable than Dillon.