is Sql Server AlwaysOn AG a multi-site active-active replication technology?

Scenario FCI: I understand multi-site active-active replication in SQL Server can be installed with an FCI (Failover Cluster Instance). The replication part occurs at the storage level with a connected SAN. So it’s considered active-active, but only one node has the FCI ownership, but the data is replicated between sites at the storage level.

Scenario AG: But, I’m searching for a widely accepted definition of active-active replication. In Microsoft’s documentation, the secondary replica in an AG (Availability Group) is active if the same can be used for read-only queries. So, an AlwaysOn AG could be used to get replication between the two sites, with the primary active read-write and the secondary active-read-only.

So the difference is:

Scenario Main Site DR Site
FCI read-write read-write
AG read-write only-read

So my question is: I’m seen that FCI with synchronous storage level replication is considered active-active replication. But, I’m seen too that active-active replication is considered only when you can read-write to both sites. So, my questions are:

  1. is there some widely accepted definition of active-active replication?
  2. Scenario FCI and scenario AF are considered active-active replication?
  3. what’s the difference between active-active replication and master-master replication?