The substantial difference is that actors act on messages while agents are only pieces of data with an assigned thread (in a pool, doesn't matter) that is sched

The substantial difference is that actors act on messages while agents are only pieces of data with an assigned thread (in a pool, doesn't matter) that is scheduled to retrieve the functions passed via send and send-off. There is an amazing talk from Rich about clojure concurrency where he implements an ant simulation with agents, it's really great. He also mentions the difference between the erlang and the clojure model in a much better way than I possibly would.