per Allan Hirt

it is:  AlwaysOn (one word) Availability Groups (AGs) and AlwaysOn Failureover clustering Instances (FCI).  AlwaysOn (one word) is a marketing term for AGs and FCIs.

and it is:  A two node Microsoft Failover cluster.  One node is always active in the instance.  You can have a two node, two instance cluster, with each node having an active instance running on it.

Or since you can have several SQL instances on one machine, you can have a three instance Windows Failover cluster running on two nodes.  Exactly where the instances are running at any time is a configuration issue, not a description of the environment.