My favorite contrast between the stories so far are the protagonists' internal struggles.
Bong Soon in the orginal series struggles to accept her strength and hides it from the outside world. She worries that she won't be loved because of it and acts "weak" around Gook Doo. Her journey throughout the series is to accept herself and use her strength in order to help others.
Namsoon, on the other hand, sees her physical strength as something to be proud and openly expresses her strength. The story isn't completed yet, but I think her journey will be to no longer to solely rely on her strength without being cautious. (I believe this is foreshadowed by Hee Shik's and her father's warnings.)
Bong Soon feels like her mother doesn't see any value in her other than her strength. She feels like her mother loves her brother more. Namsoon on the other hand is immediately beloved by all of her family, especially since she was missing for so long. Her brother is the one that feels like he is being left out.
These internal struggles also coinsides with their romantic journey's.
Min Hyuk loves Bong Soon wholeheartedly while knowing her strength. Even after losing her strength he continues to love her. He loves her as she truly is, while before Bong Soon felt like she had to change herself.
Similar to Min Hyuk, Hee Sik seems to care for her regardless of her physical strength. However, unlike Bong Soon, Namsoon doesn't require that reassurance. I am GUESSING that this will contrasted with the Shi Oh's obession with her strength. He seems to think that she is fearless(invinsible to an extent), while Hee Sik recognizes she can still be hurt.
