Korra definitely had the question about artes being magic and not magic, because to her, it was all just magic.

But what threw her off asking that was "Wait, you can make someone stronger or beefier?" All she could think of was the gift Eshai had given that imbued Korra with a temporary surge of strength, one she hadn't used yet. "How does that work? You can't just make muscles appear, right?" Magic's weird, she'll give it that, but for her; this one took the cake.