The plot is similar. The ML hires FL to be his fake wife as his real GF was away and he needed to avoid the arranged marriage. And later, he fell in love with her.

similar plot. ML is coming back from a foreign country after finishing the study. FL is someone who grew up in the same house and later, fall in love with ML.

similar plot. ML is coming back from a foreign country after finishing the study. FL is someone who grew up in the same house and later, fall in love with ML.

similar plot. ML is coming back from a foreign country after finishing the study. FL is someone who grew up in the same house and later, fall in love with ML.

The similar plot, the relationship between brother-like ML and niece -like FL. FL is surrounded by mean relatives and ML is the only one whom FL can rely on.

The similar plot, the relationship between uncle-like ML and niece -like FL. FL is surrounded by mean relatives and ML is the only one whom FL can rely on.

The similar plot, the relationship between uncle-like ML and niece -like FL. FL is surrounded by mean relatives and ML is the only one whom FL can rely on.

The similar plot, the relationship between uncle-like ML and niece -like FL. FL is surrounded by mean relatives and ML is the only one whom FL can rely on.

FL is also a princess, who will be the crown princess later in the story.
ML is a soldier and bodyguard to FL, who will protect her all the way.
The main differences are that SJJ is a period drama and its characters have some supernatural power as far as its aired episodes.