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.
Dummies Guide to SQL for THIS dummy 