The issue is nonconsensual intimate visual depictions. Sites have to take down such content on request. If they don't have a policy that satisfies the requirements, the FTC might issue fines. If they don't follow valid requests, there might be fines/criminal charges. I guess the situation might be more problematic for users who are uploading such content, as they might be criminally liable. (The respective law was enacted a little more than a year ago.)
Yes. The difference is that the whole purpose of that site was to publish and distribute such content. CHYOA is a site for user-generated content and has implemented a policy to meet the requirements of the act. Thus, content that falls under the definition in the act will be removed on request as outlined in the policy. The only images hosted on CHYOA are cover images and avatars. All other visual content is hosted on other sites and just linked to on CHYOA. I assume that these links are also covered by the act and thus will be removed on request. For users who knowingly create and publish such nonconsensual visual content, the situation might be different. I assume that the focus is on removing the content, though I might be wrong.