Written
A ChronoForms Action does something: sends an email, displays your form, redirects the user.
A ChronoForms Event sets the time and sequence for the Actions.
For example, the On Load event sets the Actions that are run when the form loads in the browser; and the On Submit event sets the actions that run when the user clicks the submit button and the form results are sent to the server.
And that really is all that you need to know. All of ChronoForms v4 is built around those two facts.
I have written a tutorial document explaining much more about events and actions with a description of all the CFv4 basic form actions. You can download it from my site {rokbox text=|here| size=|1000,600| }http://greyhead.net/how-to-docs/cf-v4-basics-2{/rokbox}.
There is a list of the current actions here