It might have a different theme. Previous storylines could have focused on one aspect of the game world, while the new story could explore something new, like a different region or a new conflict.
The new story could introduce new gameplay mechanics that are tied to the story. For instance, if the new story involves a new type of magic, there might be gameplay elements where players have to use or counter that magic. This is different from previous storylines which may have had their own unique, but different, gameplay - story integrations. Also, the art style might be evolved in the new story, with more detailed environments or character designs compared to before.
The new story may have more complex characters. In comparison to the previous storylines, the characters in the new story could have more intricate personalities and relationships. This can make the story more engaging as players get to discover and interact with these complex characters. It could also have a different pacing. Maybe it's faster - moving with more action - packed sequences, or slower, with more focus on character development and world - building compared to the previous storylines.