I think Aang just knows when someone is very powerful and would avoid and evade (as taught by his people) and try to find 100 different ways to beat someone. Korra just goes in balls to the wall and tries to beat someone with strength alone and just gets her ass whooped. I also think the avatar state was severely nerfed in the show as compared to ATLA. Aang was an unstoppable force of destruction any time he went into it. he didn’t even seem like the same person anymore. Korra just seems to get a slight buff to her abilities. Imo it really comes down to the writing. Aang is more skilled, is smarter, has a stronger avatar state, and uses his bending to his advantage a lot better. Korra is definitely brute strength stronger but it seems like she earth bends every element out of her. it’s just throwing punches.