At 5v5, through 2 periods, the Maple Leafs had 21 shots on goal and 19 scoring chances, 7 of which were of the high danger variety.
Tonight, at 5v5, through 2 periods, the Blues have 18 shots on goal and 16 scoring chances, 6 of which are of the high danger variety.
I think there's a difference in their play for sure, but I think it can be mostly explained by competition, and that the biggest difference in the 4 goals against through 2 periods Vs. Toronto, compared to the 0 through 2 against St. Louis, can be explained by goaltending more than any other factor.
Limiting it to just 5v5 is purposely not telling the entire story. Through two periods, the Sharks gave up 29 shots, somehow 31 scoring chances, and 12 high dangers compared to 19 shots, 17 chances, and 6 high dangers. Granted, some of this difference is that the Leafs are a much different and better team but the defense is better and the turnovers have been mitigated.