Will it Snow for Christmas? (2009)

Both have unforgettable love and intertwined family fate. Both have a gorgeous couple with great chemistry. Fortunately, one has a happier ending.

both dramas are heart braking and make you wanna cry.

It is both about pretending not to know each other but this time it's the lead man who pretends to not know the girl.

-Both are tear-filled ROMANCE MELODRAMAS where the leads know each other for years and struggle to get maybe together
-Both have EXCELLENT main pairing with great CHEMISTRY

They have some common points (i.e. love triangles or one character come from a poor family) and their genre is the same ("Will it Snow at Christmas?" is especially melodramatic)

it is a completion for the sweet love/pain drama that takes ur breath away

Padam Padam is the better drama if you're limited on time. Though, both dramas deal with a huge mother-son relationship. The characters' lives also feel like a similar tone. All of them have problems and it deals a lot with a slice of life even though they're melodramas.

These dramas have so similar vibe. Both are melodramas, telling about people who fall in love, for some reason can't be together, but fate won't keep them apart.
Both have iconic time skip, which is very important for the plot - first few episodes are about teenegers, and next, longer part is about couple in their 20thies. In Love Rain, second part is focused on previous character's children, while WISFC focuses on the same pair, but after time skip.
Still, in both dramas not only children, but also parents of them fall in love with each other (they live in unhappy marriages).
Those are melodramas at its finest, so please bare in mind that it may be hard to watch because of its overwhelming so-called sadness. Not to mention that topics such as death and sacrifice happiness are present. Forbidden love is the most important theme though.
Definitely worth giving a try if you like The Bold and the Beautifull melodramatic vibe.

both dramas are heartbraking, but it still makes you want to watch more.

-Both are very angst and tear-filled ROMANCE MELODRAMAS where leads know each other for years, and struggle to overcome obstacles in order to be together
-Both feature a class difference between leads
-Both have EXCELLENT CASTING & LEAD'S CHEMISTRY and they can act too. Casting for other characters is great too (Shout out to JO MIN SOO who plays male lead's mum in WISFC, AMAZING actress!!)
-Same structure: Both love stories start out in unsatisfying way/too fast/unbelievable. DON'T be discouraged by the starts of the loves, it gets REALLY shippable/more believable later on & they have EXCELLENT chemistry. Both have an ambiguous/mini ending type of episode some eps before ending that can be seen as ending if not satisfied with real ending (ep 11/16 of WISFC and ep 16/20 of LITFC)
-Both have strong female leads

-Both very underrated dramas
-Both are very sad/emotional, and thus only recommended to those who love sad stories (NOT for everybody!)

-Both have GREAT OSTs, that supports love story really well / makes you ship them more!

DIFFERENCES:
-WISFC is a korean drama, while LITFC is a chinese drama (which reminds me more of a kdrama! A cdrama for those who normally don't like cdrama. Also NO dubbing over their real voices in this cdrama!)

-Both ROMANCE MELODRAMAS by the same writer with EXCELLENT leads that are perfect together, GREAT CHEMISTRY and can act (Go Soo + Han Ye Seul & So Ji Sub + Im Soo Jung !)

-Both have strong/likeable female leads who are annoying at the beginning since they have a 2nd lead/male, but grows lovable

-Allthough both dramas are good, ISILY is better (10/10!)

DIFFERENCES:
-ISILY has a REVENGE element, no such in WISFC
-ISILY is MUCH more heart-breaking, especially the tragic childhood/background story of the male lead