Positionally mainly I think, the whole team was at least 10yrds higher from starting positions.
Kane, Son & Lucas also went more laterally but still narrow (still had one of the 3 drop deep but they weren't standing on each other's toes). But this was aided with Winks and PEH dropping even deeper pulling out Foreshaw (who I thought along with Phillips was excellent) which then led to a defender being pulled out when one of the 3 dropped deep. Just doing this created the space that wasn't there in the first half (in the first half Foreshaw wasn't isolated, he was in 2nd half)
Also, with both PEH and Winks dropping even deeper alongside CB's meant with Leeds man-marking them they created the space for Dier to bring the ball out.
Finally, our WB's pushed much higher too, which forced Leeds into a back 4, with us pressing higher they were pinned back and unable to keep the ball (much as we were in the 1st half). All this was underpinned with us playing more aggressively and outrunning them and making 1st & 2nd ball before them.
Conte alluded to some major tactical change, I'm fucked to spot specifically what that was! To my eyes, it was just tweaked (as per above) to the positions intended for the first half but just much more aggressively and positively applied. ???