Since your query is specifically for Spotify genres, then I think it would be useful to check out Every Noise At Once. You can try searching for these artists using the search bar top right of the website and find out what are the assigned genres. :)
For example - Massive Attack appears in the genre clouds for electronic, downtempo, trip hop and big beat. (matches the user-assigned genre tags on last.fm pretty well).
Note: the map is in no way a final static product - it's an everchanging map and as it learns, it changes shape.
Hope this helps, have a lovely day :)
SebastyRock Star 15
Help others find this answer and click "Accept as Solution".
If you appreciate my answer, maybe give me a Like.