> can you describe the differences via poorly-suited metaphor in uncooperative words, please?

Oh, yes, that's my favourite. :P

They do the same thing, or part of the same thing, but they do it in very different ways. The little bird's power is very outward, like I said; it goes outward from her to the person she's protecting and then looks outward again to guard them. Bridget's power is very, very inward. It works on her, not on the world around her. And it's big and small at the same time, like there's really three times as much Bridget as the world gets to see, trying to press itself down into just slightly less space than she nominally occupies. (Powers looking a little smaller than their people isn't unique—Kolya's does it too—but I've never seen one be simultaneously bigger like that.)