Björn Schießle is a user on mastodon.social. You can follow them or interact with them if you have an account anywhere in the fediverse.
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@ink_slinger
As already said by others, Mastodon and Diaspora don't really federate. I see them as the two big islands: Diaspora and OStatus/ActivityPub. So if you don't want to miss parts of the fediverse you could either be on both island or use Friendica which bridges to both. Beside that you can see them as Twitter (Mastodon) and Facebook (Diaspora) from a technical point of few if you want to think in this terms and if you are more familiar with the differences there.
@bjoern I was on Friendica briefly. I liked that it technically federated with both parts of the federated world, but found it overall not great. It didn't seem to properly federate with diaspora and that lack of full integration quickly became frustrating, since there are way more people on diaspora than Friendica, so most of the people I was interacting with were on D*.