What exact criteria we have to distinguish between these is as yet unclear. An intentional action seems to require the agent to have a mental state of an intention, which seems different from a desire. The exact differences are yet to be explored. Several shades of intentions were discussed. Not all intentional actions seem to have elaborate prior plans.
Some intentional actions are spontaneous.
One possibility is that such actions, too, have prior intentions-but a split second before the action's performance begins. Another possibility is that there is another type of intention-intentions in action. In general, at least one belief and one desires, but more realistically, a network of many beliefs and desires provides the reasons for intending to do something. People then explain intentional actions by citing one or more of those reasons.