Final answer:
The most noteworthy difference between girl groups and doo-wop is the focus on instrumental arrangements by girl groups, compared to the a cappella vocal emphasis in doo-wop.
Step-by-step explanation:
Girl groups like the Shirelles, the Crystals, and the Ronettes are often seen as a continuation of the doo-wop tradition, but with some significant differences. The most noteworthy difference between girl groups and doo-wop is that girl groups focused more on instrumental arrangements, while doo-wop placed a stronger emphasis on a cappella vocals. This trend is part of the evolution of rock and roll, which itself was a combination of electric instruments with the sounds of gospel, blues, country, jazz, and R&B, becoming an instant success with its heavy rhythm, simple lyrics, and captivating melodies.
Doo-wop, on the other hand, often featured male vocal groups and was known for its tight harmonies and lack of instrumentation. This genre also started as a form of Rhythm and Blues, predominantly created by Black artists, and was part of the cultural movements and musical innovations that defined American music in the post-war era.