In Miller's first game back after suffering neck injuries in the Lucic hit, Tootoo skated hard toward the net and made no effort to avoid contact with Miller, who was in his crease. That detail is the biggest difference between the Tootoo collision and the Lucic hit, and it's one of the reasons Brendan Shanahan decided to suspend Tootoo and not Lucic.
"The goaltender must be protected in his crease," Shanahan said. "It should be noted that interference on the goalkeeper can be penalized with a minor [penalty]. There will be times when the contact with the goaltender and the call on the ice will be suitable for the offense. However, we feel the on-ice call of charging and a game misconduct for this particular offense was correct, and that the supplemental discipline is necessary because of the force of the collision and the lack of any significant interference steering Tootoo into the goaltender."
You can watch Shanahan explain the suspension fully in the video below.