I created an expanding blog entry on the different types of chatbots.
Posting it here in case anyone else finds it useful, or is confused by all the different types of chatbots,
So far its defines,
[ul]
[li]Virtual Agents[/li]
[li]Chatterbots[/li]
[li]Knowledge bots[/li]
[li]Twitterbots[/li]
[li]AI bots[/li]
[/ul]
http://botlibre.blogspot.ca/2015/05/what-is-chatbot-chatterbot-virtual.html