Both blues and rap are arbitrary labels generally provided by recording companies to market their product. There are many forms of both. Early rap was like blues in that it conveyed the history of the African-American experience. The two are tributaries of the same river.

One hallmark of an expressive song is its specificity in imagery. Both blues and rap serve this purpose. Blues and Rap both have a tendency to glorify the myth of male superiority and bravado. This is an essential element because of the emasculation of the black male in white society. It's an attempt to say "I am somebody".

The blues and rap you hear on the radio is often uncharacteristic of the music found in the "hood" or in the deep south.

Blues evolves as it is exemplified by Charlie Parker.

Rap and Blues finds their way into jazz and as a verbal vehicle of expression of a kind of folk poetry, emanating culturally from the Griots of Africa.   Both Blues and Rap tell the story of Black suppression. For that matter, jazz started that way also from Congo Square in New Orleans through to John Coltrane or Esperanza Spalding.

Both form a firm foundation for the evolution of African-American music. There is no versus here but a remarkable cohesive connection which has enriched the musical culture of America and cultures worldwide.