I'm not sure specifically as it could be many things. It might be a typical love story about two people falling in love, facing challenges together and finally getting together.
Sanam Tere Kasam is a romantic drama. Saif Ali Khan's character goes through a journey of love. He falls in love with the female lead and they have a relationship filled with ups and downs. They face family opposition and social challenges. However, their love is strong and they try to fight for it. In the end, they either end up together or face a tragic separation, depending on how the story unfolds.
The key elements include the relationship between Saif Ali Khan's character and his love interest. Their love is at the center. Also, the social context matters a lot. The society's expectations and restrictions play a big role in shaping the story. And of course, the individual growth of Saif's character as he navigates through love and challenges is an important part.
Since I don't know the story itself, I can't say for sure about its significance. But generally, stories often carry cultural, moral or historical significance.
Since I'm not aware of the 'Mehndi Tere Naam Ki' story, it's difficult to determine the main plot. However, if Mehndi is a person's name, perhaps the story could revolve around their relationships, dreams, or a journey they undertake. It could also be related to the significance of mehndi (henna) in a cultural or symbolic way.
I'm sorry, I'm not familiar with the specific story of 'pyaar ki yeh ek kahani'. It could be a unique love story from a particular book, movie or cultural context.