The biggest difference I notice from the 1970s (which I think was the greatest decade musically) is the breadth of what was popular (along with how great the rock bands were). Picked a random week in 1975. They all look like this. Country, disco, rock, southern rock, motown, pop, whatever category Neil Sedaka is.
US Top 40 Singles Week Ending 25th October, 1975 - Top40Weekly.com
Same week in 77 and you've got the Star Wars cantina song #1, Foreigner, Ted Nugent, Carly Simon, KC & The Sunshine Band, Commodores, Barry White, Frampton, Bee Gees, Steve Miller, Donna Summer, ELO...it's just kind of wild. You probably remember listening to all those songs, even if they weren't your style.
US Top 40 Singles Week Ending 25th October, 1975 - Top40Weekly.com