Passage A is adapted from a book by a music historian, and passage B from an anthropology journal.
Passage A
This author seems to introduce but then resist a comparison between griots and blues musicians, saying they have incredibly different sociological status.
The griot is the protector of the West African culture; they served a vital function in binding the community.
The blues musician reflects a lack of connection to community. They are alienated and unwanted. If there's any parallel at all, it would be that the pain expressed in blues music is the pain of being separated from the rich cultural history of West Africa via slavery.
The last paragraph distills what the author thinks is precious / special / essential about blues music: it tells incredibly small, personal sad stories as a way of silently acknowledging a big, communal sad story (slavery).
Passage B
This passage is just an informative discussion of griots. - lowest caste - most skilled when it came to spoken word - sung praises of their host family - tried to curry favor for their host family with the public - considered guardian of much of the cultural history and norms, and thus operated within the boundaries of cultural expectations
Similarities
Both passages cover griots, saying that the griots are important members of the West African community, heavily involved with the culture's norms and history.
Differences
Passage A is mainly about blues musicians. Passage B is only about griots.
Passage B's discussion of griots goes into much more depth.