I'd say that's a vague antecedent. The tense of Philip's phrase suggest that he's referring to something in the present (can you), as though telling the difference between them is an ongoing problem; while if he was referring to events in the past, he should have said 'could you tell the difference between them'.
Edit: that said, you would generally assume that a vague antecedent would refer to the most recent appropriate noun, which, in the context of Obama's comments, would have been the meetings, not the people.
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