Redhat rolled out Openshift version 3 which is having a totally different architecture than its earlier version referred as 'Openshift' or 'Openshift V2'.
Please check the details here.
All the queries on Openshift V2 or earlier are commonly tagged as 'openshift'. However, the same is no longer valid for Openshift V3. While Openshift V2 and V3 would co-exist for some time, it is more appropriate to tag all V3 related queries under this tag (Openshift-3).