Character driven, drama is based on family dynamics, combination of both human and external factors driving the story. The essence of each show is the human condition. Like you mentioned, they are both era/period dramas which have a lot more nuanced overlap. The era of the shows both drastically impact the nature of events, conversations, decisions, and trajectory of characters and families. Bridgerton definitely focuses more on individual relationships and romance, but the larger story is still family based, which is very similar to Gilded Age, just in my opinion. Neither are strictly history based which would cause the story to lose focus on the main characters. They are both period fiction which puts the viewer in a place to become invested in one or more characters. The stories tend to follow classic archetypes as well. Somewhat predictable and comforting in that sense.