First of all they are not similar at all. I recommend this only to those that wish to see a whole other side of Lee Soo Jin and his acting. One might even say that they are polar opposites seeing that one is a light comedy while the other is a tragic melo. If you need a good cry after laughing or the other way around do give the other a go.
Starlit does not have the ML or FL drenched in wealth beyond belief it really shows how humans suffer to make their love work when the one they love can be taken away with the next breath. Marriage Contract has the rich ML but no amount of money can buy more time to love the one he loves. Neither drama offered up magically cure.