The difference is there is no not choosing to use client-side scanning. I could choose not to use apple cloud services for photos and therefore not participate in server side scanning. Essentially, client-side scanning assumes everybody's guilty until proven innocent. It's a slippery slope for scanning local content. Today the admirable goal of eliminating child pornography and maybe tomorrow FBI most wanted list, then pretty much anybody in the criminal system. Not to mention the political implications.

You see this as a simple trusting apple because they have complete control over the OS/Hardware. I see this as a culture shift that goes beyond trusting any particular company that fundamentally erodes privacy.