Different stories but same feel. Similarities between the two are:

1) Smart and Witty FL
2) FL has a different love interest initially
3) ML falls in love first
4) Once the Lead couple get together they are loyal and trust each other
5) Both are slow paced drama
6) Amazing chemistry

If you like one, definitely give the other a try.

I watched Raeng Pradtanaha few years ago, it has some similarities between the two stories. Rich FL who is spoilt and mean to the ML. Both Leads grow up in the same household. ML is like an adopted son to FL's parents and ML works for FL's Father.
However the story line between the two series is different.
Both series are a good watch.

Both the movies have good chemistry between the characters. Simple love stories with not lot of complicated characters.
Both movies have a drama version.
Both the dramas are better than the movies, as you can see the growth in the characters. Would recommend watching the dramas related to these movies as well.

Both the dramas have quiet a different story line, however the romance in both the dramas are interesting and refreshingly different.
Main leads have great chemistry in both the dramas. The supporting characters are also quiet interesting and have their own story line.
Both are light hearted romantic comedy, if you like one don't forget to give the other a try.

Both the drama gives the same feel. Not much of negative characters. Lots of cute moments between the main characters.
In both the dramas leads meet in university.
However the story line is completely different. If you liked one, don't miss out on the other.