Hi, thanks for the tag. Free for the user is likely what he is mentioning. Vector is free to use for anyone, as is Nostr. Yes, it does cost to host Nostr Relays, but the end-user does not have to pay for that or contribute to it if they don't want... hence, the freedom to choose.

Correct, iOS is not available yet for Vector.

The biggest difference is that you can see how Vector operates because it's entirely open-source and decentralized, rather than having to rely on documents and a privacy policy, ultimately blind trust that no one else can verify but those authorized to do so.