Holding down (d-pad) in PVE causes the map to expand / blow up on the screen.
In PvP it doesn’t (for me, anyway). Which makes it very annoying to figure out where the shards are, or which lane the giant minion was sent down in meltdown.
I assume this is to accommodate the teleport feature, but I seem to remember that in the CTT you could do both (teleport and map)