What is the "essential character" of a dispute?

In Weber v. Ontario Hydro, supra, McLachlin J. stated at pp. 956-7: In considering the dispute, the decision-maker must attempt to define its “essential character” .... In the majority of cases the nature of the dispute will be clear; either it had to do with the collective agreement or it did not. Some cases, however, may be less than obvious. The question in each case is whether the dispute, in its essential character, arises from the interpretation, application, administration or violation of the collective agreement.

And in New Brunswick v. O’Leary, supra, McLachlin J. reiterated this position at p. 970: ... However, as noted in Weber, a dispute will be held to arise out of the collective agreement if it falls under the agreement either expressly or inferentially.... Again, it must be underscored that it is the essential character of the difference between the parties, not the legal framework in which the dispute is cast, which will be determinative of the appropriate forum for settlement of the issue.