They are run by different people, though there is a lot of cross contamination and groups going to both.

I think the real difference is the setup, CCC is in a exhibition hall, while events like WHY are on a field and require you to camp. In that regard, you can compare CCCamp (what is different from CCC) more with WHY.

I had a great time at PyData Amsterdam last year. Terrific people!

I always like Fosdem (in Belgium, very close.)