The former Scotland manager has been brought in by new owner Ann Budge as part of the restructure at Tynecastle which has also included the promotion of former defender Neilson to the manager's seat.
The 33-year old has replaced Gary Locke as Jambos boss and will be the man to oversee all things pertaining to the team despite the presence of the much more experienced Levein.
"My responsibility as the director of football is overseeing everything that's involved in the football department," Levein said.
"It's much better in my mind that my thoughts and Robbie's thoughts and the other coaches' thoughts are aligned on how we see this thing working.
"We've already got this agreed at board level. I don't want to pick the team, I don't want to pick the players: unless I let the coach make decisions how is he going to improve?
"That's the crux of the matter. I can't make those decisions, because Robbie Neilson has to stand on his own two feet. I'm there to help and on a Thursday - and this is for Robbie's benefit - we will sit down and discuss the tactics for the Saturday, who he's going to play, why he's going to play, how he sees the game going. And then once the game's finished we'll sit down on a Sunday to do a debrief and we'll go through the same process and talk about what we'll do next week that will help."
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