Maguire can take too many touches of the ball sometimes but he's much more assured on the ball, Lindelof can't pass and he isn't quick enough to partner Maguire.
It's not that Lindelof is bad, it's just he isn't at the level needed to challenge for EPLs and CLs.
Lindelof would make a fine squad player, but not a starter.
My issue with Lindelof is besides defensively he offers nothing, and at a top club given how the game is now, you need to be able to pass and play from the back.
When I say about passing I mean probing balls to find a midfielder in between the lines, or a ball to release a winger on the far side.
If teams are doing a high press you need to be able to punish them releasing wingers or probing to find a midfielder, you can't just do a square 4 meter pass like Lindelof does.
In games that United are really tested (top 4) and in Europe, Lindelof doesn't meet the standard that you would want, nor does Bailly.
Until the end of the season Lindelof is the best pairing, but to win leagues there needs to be a top top player to partner Maguire.
Bailly and Lindelof are great squad players, that is about it.