Smart and business-savvy female lead. Both FL's have calm temperament and approach their problem and family matters/concerns with a composed attitude. Both are also have good relationship with their grandfather's. The male leads are both dependable men and apparently common with the double identity trope. The ML's hold high positions in society but have a complicated distant connection to the palace/imperial family. In short, both dramas are about, double identities (male lead) and business/merchants (female lead).
Quite similar in main aspects, FL family got downed because of problem with government and FL took over the household affair, with sweat and tear leading the family to be one of the most wealthy family. Also, ML also join in political. HOWEVER, thought NGCS is a masterpiece and very very aspiring, it's needed brain power to watch, BIA is simpler.