I love Fluxer! Hampus is cool and what he's built is super impressive.
I would say the primary difference is that Chatto doesn't squarely aim for being a _Discord_ alternative. There are no plans for providing a Discord-compatible API (which I think Fluxer does.)
The other main difference is that Chatto is designed, on purpose, to serve individual communities from tiny deployments, instead of large mega-instances that power many communities. Chatto deliberately avoids content federation to remain compatible with business use cases, and also to stay simple enough so it can run from a single binary.
I would say the primary difference is that Chatto doesn't squarely aim for being a _Discord_ alternative. There are no plans for providing a Discord-compatible API (which I think Fluxer does.)
The other main difference is that Chatto is designed, on purpose, to serve individual communities from tiny deployments, instead of large mega-instances that power many communities. Chatto deliberately avoids content federation to remain compatible with business use cases, and also to stay simple enough so it can run from a single binary.