These are the official “neighborhood planning clusters” as adopted by the Community Revitalization Strategy (CRS) in 1997. The city’s master planning efforts are still bound to these ten planning clusters even though the city has numerous other methods for identifying and prioritizing geographies.
I found this on Detroit’s ancient GIS webpage using the Internet Archives’ Wayback Machine. There’s just something wild to me about the color choices. I wonder what GIS software had these are defaults or how the mapmaker chose this palette of baby blue, pink, and light yellow.