I have the sense that the Yankees schedule so far has been easier than the Sox'. For one, they have consistently been 3-5 games ahead in home games since the start of the season. They spent a good deal of time at home in April, for example, while the Red Sox were starting very slowly on the road.
The schedule differences are supposed to even up by season end, but I'm not so sure because of the nature of the scheduling, with divisions and interleague play, etc.
Were it not for the huge (10-2?) face to face advantage vs NY, the Red Sox might be 5-6 games behind the Yankees right now, since their record against other teams is worse than NYs. Is that because of the Sox have a tougher schedule against other teams? I don't know.