Difference between worker threads and sessions in SQL Server
It depends on the session's execution plan. If a session executes a query with a serial plan then yes, you can say 1600 queries, but if it runs a query with a parallel plan, then a session can have multiple worker threads per session.

Tasks, Workers, Threads, Scheduler, Sessions, Connections, Requests – what does it all mean?


  Worker (worker thread) – This is the logical SQL Server representation of a thread (think of it as a wrapper on top of the OS thread). It is a structure within the Scheduler which maintains SQL Server-specific information about what a worker thread does. sys.dm_os_workers. Workers are the humble servants who carry out the task assigned to them by the Master (scheduler).
  
  Sessions – when the client application connects to SQL Server the two sides establish a "session" on which to exchange information. Strictly speaking a session is not the same as the underlying physical connection, it is a SQL Server logical representation of a connection. But for practical purposes, you can think of this as being a connection (session =~ connection). See sys.dm_exec_sessions