Both dramas are from the same writer and both have many actors in common. Some themes are featured in the two dramas, like wars for power and money, revenge and betrayal. The writing style is similar, except Giant doesn't have the humor/comedy situations factor.
Same creators. Bot have totally awesome characters and story. Both have a lot of comedy, but on the other hand there are some really serious moments too. It takes some time for story to develop, but when it does, everything falls into the right place. Both are one of the bests dramas you can ever see (which is definately not an overstatement!)
Both dramas' plots are of revenge against another for the sake of his family. Both main characters are in the field of law practices. Throughout the dramas we get to experience their pain and how they have became strong to fight against those who are in power. The main characters' stories are both very tragic, very well written plots.