Similarities according to me:
Same female lead short and cute
Sporty good looking male lead
University life

Similarities according to me :

1.Same handsome Male lead
2.Cute Female lead
3.University life
4.Leads in similar fields

The thing which are similar:
Age gap
Student teacher relationship
Marriage because of elders
Living together ofcourse bcos of their marriage
(But falling in love anyway:D)

Not very similar
Except
for the part that female lead blushes uncontrollably
Male leads are handsome

In both the dramas
They show uni life
Leads are into art
Very handsome,popular ML
Short cute FL
Same SML
ML was interested in the FL since way long back but FL didn't know

The similarities lie in some scenarios like
Marriage out of love but then start fighting badly so much that they throw things here and there and want to divorce
Falling in love again
Similar looking female leads
Same work place

The similarities are
rich famous male lead
Hate to love relationship
Tsundere personality of male lead
A Scene where leads are lost in a snowy place

There's this cross dressing in both...FL shares room with ML
SML likes FL not knowing she is a girl
ML lead gets to know about her gender and secretly protects her

The synopsis is similar
like how they are showing students preparing for college entrance exam
The things the students and their parents go through

Playful kiss is a kdrama version of it started with a kiss , Male lead is popular and very smart , the female lead is kinda dumb and chases after male lead even if he completely shows no interest in the start for a long time