Similarity:
- Both male leads grow up poor and then try to infiltrate the wealthy upper class to gain power.
-There is a lot of emphasis on social class and wealth in both, which is my main point of why oyu should watch both.
- Both ML's have tough relationships with their families, that improve as the story goes on.
- Both ML's leave the female lead to pursue their plans only to realize that it's not worth it to go on with her.
- Both ML's are originally shown to be socially inept and apathetic toward others in the beginning (but of course that changes).
-Both get the justice they seek, but in two very different ways.

Differences:
While in both Good Bad Mother and Golden Spoon the ML completely disregards their families, in the GBM there is a lot of emphasis on the relationship between the mother and the son. Yet, in Golden Spoon, it's focused on his family and friends in general.

They're both so good and dramatic. I recommend.