The difference is that there's competition in the hosting/domain business. So if you're denied services from one of them, you can still get hosting by going elsewhere. If you can't go elsewhere, then we can all be assured that dozens of people at various companies have looked at it and chosen not to host it.
And if you don't want to accept that, you can probably still get it hosted (with enough money) by building a data center in some place that doesn't care.
In the ISP space, there's no competition for a good many people. One person looks at content, decides it's not worthy, and it's blocked period. No appeal, no asking others for their opinion. And if the end user doesnt like it, they can move, sell their house, find a new job in another area.
That's a much harsher, draconian result.