What are benefits of AlwaysOn FailoverClustering vs AlwaysOn Availability Groups?

Basic AlwaysOn Failover Clustering provides server level protection,  (Eg: 2 servers with 1 shared disk space;  if server fails, it can utilize another server on the shared disk space).

AlwaysOn Availability Groups provides both diskstorage DR with server-level HA Protection. It provides 2 servers with 2 shared space.
(a) so what benefit functionally does AlwaysOn FailoverClustering have over Availability Groups?  Seems Availability Groups is better, Looking at the chart comparison I see none

(b) Can AlwaysOn Availability Groups utilize with  1 server, 2 shared storage space? (instead of 2 server, 2 shared storage?)


[![enter image description here][1]][1]
We utilize SQL 2016 Enterprise.
Thanks,

Reviewed documentation: [Failover Clustering and Always On Availability Groups][2], [SQL AlwaysOn][3]


  [1]: https://i.sstatic.net/FGYz6.png
  [2]: https://learn.microsoft.com/en-us/sql/database-engine/availability-groups/windows/failover-clustering-and-always-on-availability-groups-sql-server?view=sql-server-2017
  [3]: https://www.mssqltips.com/sqlservertip/4717/what-is-sql-server-alwayson/