To avoid getting yelled at by cyber warriors, I’ll keep it short.

K version:
short and sweet
More like neighbors than family which helped the transition to lovers
No stupid love triangle
More on second leads
Dal power- enough said
FL is not as strong of a character, more pouty and childish

C version: in depth and longer
More like family since the build up took more time
More family scenes and more character developments but it made the transition to lovers a bit more awkward
That dreadful love triangle
More scenes for the side characters

Overall, watch both. Definitely one of the best slice of life.