I watched both the series about an year apart. I wasn't going to watch this one because I already saw the original version and I thought, it would be same ( like Kiss me series - I watched Korean and Japan version. they are exact same). Surprisingly, I thought I was watching a completely different drama.

Major difference between both:
1) The K-version spends a lot of time on the SFL. The guy is always running around her. However the Thai version spends more time on the ML's.
2) Since Thai version has more time on ML's.. it has stronger chemistry between the leads.
3) The ML in K-version is jerk but the ML in Thai version is better.
4) I would categorize Thai version as Rom-com but K-version as Romance. The comedy in thai version is better.
5) The Kdrama provides a bit of sad feel.. but the thai version provides more of rom-com feel.

If you want to choose between watching one of the two.... I would say go for Thai Version.. It is more Romcom