Microsoft have changed the name of First Release, to Targeted Release.
Where in the past first release would get things straight after the internal Microsoft teams have finished their testing and before everybody else gets releases in the Worldwide standard release now this will be called Targeted release.
Within the Targeted release still has the two options Targeted release for everyone and Targeted Release for selected users. Also the settings are still in the same place so not much has changed other than a name of the update ring.