The Kennedy Center presented a double bill on Saturday evening that showed two very different approaches to modern acoustic jazz. Saxophonist Branford Marsalis and trumpeter Terence Blanchard are both titans of the genre, with strong pedigrees in the musical traditions of New Orleans. Marsalis’s quartet adopted a less structured sound that was more adventurous and challenging, while Blanchard’s quintet dug more into the swing of things and offered more accessibility during its half of the two-and-a-half hour concert.