Ginza vs Mastodon · two non-Facebook answers
Mastodon and Ginza are both reactions to Big Social, but they are different shapes. Mastodon is federated microblogging in the Twitter tradition. Ginza is a centralised friend-network in the Orkut tradition.
Architecture
Mastodon: federated across servers (instances). Ginza: one central network.
Surface area
Mastodon: feed of posts. Ginza: profiles, scraps, testimonials, communities. The profile is the centre, not the feed.
Who it is for
Mastodon: people who want a Twitter-shaped network without one company owning it. Ginza: people who want Orkut back.
Different needs, different answers.
If you want a profile-centric, friend-first space, Ginza is the better fit.