"Different worlds, different rules," Ilde observes, thoughtfully; she's of a similarly nerdy bent, if more stealthily so, and the things she can find and see here are intriguing even if she's obliged to rank her priorities carefully. After a moment, with a little gesture of her free hand like she's looking for a word that doesn't exist (in English-- in human tongues), "I can feel the differences? If they're magic."

It's how she picks out practitioners of similar worlds; they share commonalities in their magical signature, and compare and contrast can teach her to recognize and identify the familiar. The ability to 'feel magic' is only useful if you know what you're feeling, and she's obliged to rely on investigating those feelings in order to find out what exactly it is she's recognizing. What they do. Her own world forms a baseline, then she learns about others-- wizards of Hermione's sort are useful in how many of them she's met and how quickly she was able to separate them out from other practitioners.

"It's interesting." Potentially useful, too, if she ever finds it necessary to identify who particularly cast a spell, or who didn't.