Lease Timeout VS HealthCheck Timeout - AlwaysON After all the reading this is what I understood.  Is it correct?

LeaseTimeout is a simple heartbeat between SQL Server resource DLL and the SQL Server instance.

HealthCheck Timeout is related to sp_server_diagnostics run.

Why do we have two timeouts?

Also how do I change the LeaseTimeout?  Is it through the cluster manager because  I couldnt find any T-SQL command like below for HealthCheck Timeout 

ALTER AVAILABILITY GROUP AG1 SET (HEALTH_CHECK_TIMEOUT = 40000);
The HealthCheck is between WSFC and SQL Server. The timeout is how long WSFC will wait to get data back from the sp_server_diagnostics execution.
LeaseTimeout is the SQL Server resource and SQL Server Availability Group. How Lease Timeout works


There are two timeouts because they are for 2 different mechanisms for health of the WSFC and SQL Server. Both are changed via the WSFC property of the AG resource, picture is shown in the linked article above.