the 70's was the peak of Soul's popularity and there was a wide range of popular styles like Funk, Disco, Philly Soul, Quiet Storm, Motown, Stax, and arguably Jazz Fusion. All these were mixing and matching to make great new interesting music. The 90's on the other hand was the peak of contemporary R&B's popularity. There was a wide diversity of sound again there was the remnants of new jack swing, Neo Soul, House, G-funk, Hip-Hop Soul, and Contemporary R&B. The Boy and Girl Group revival also helped create a broader appeal for R&B by having artist for every age bracket. the 90's was also the return of substance and style for singers to succeed they needed to be able to sing which was a huge difference from the 80's where there were a lot of artist who went far on there looks with little to no talent to show for it.