"the way the terms are used is a way of mapping which apps are currently able to federate with which others:

GNUSocial, PostActiv, and Mastodon, form the #Fediverse (federating using vanilla OStatus), along with Friendica.

Diaspora* , Friendica and Hubzilla form the #Federation (federating with Diaspora*'s variant of the OStatus protocols)"

via @strypey