"Intended" vs. "intentional"

I believe the difference lies in the achievement of an objective and the motivation for it.

If I intentionally strike you in the face, I have done something deliberate and it had an effect, which was most likely to hurt and outrage you. But I could claim that my intended action was to shoo away a wasp that was about to sting you, and that striking you in the face was an unfortunate consequence (i.e., a "by-blow") of my wish to safeguard your health.

In short, the motivation for an intended act may be at odds with its consequence. An intentional act is simply one that was deliberate, saying nothing about why it happened.

An intended action is something that was desired or preferred over an alternative.

Was that your intended selection, or did you have to settle for second best.

Intended is often used to describe outcomes.

Was that the intended result, or did you hope for better?

An intentional action is one that is deliberate as opposed to random or accidental.

When you hit the lamp with the bat, was that intentional, or did you just not see it?

Intend (and hence intended) is a verb:

intend, v.

• 1. trans. To have in the mind as a fixed purpose; to purpose, design. (The chief current sense.)

Intentional is an adjective, or (obsolete) noun:

intentional, adj. and n.

A. adj.

• 1. Of or pertaining to intention or purpose; existing (only) in intention. intentional fallacy n. in literary criticism, the fallacy that the meaning or value of a work may be judged or defined in terms of the writer's intention.
• 1. Done on purpose, resulting from intention; intended. Rarely of an agent: Acting with intention.

So, it would appear that if Bob killed the cat intentionally, Bob intended to kill that cat. This is called the 'Simple View', at least according to Michael Bratman.

In experiments though, this has not turned out to be the case in practice. One famous experiment (Knobe, 2003) presented people with a vignette in which a CEO, saying he didn't care about the environment, chose to make a profit knowing it would harm the environment. 82% 0f responses said he intentionally harmed the environment.

Changing the 'harm' to 'help', so the CEO said he didn't care about helping the environment, resulted in only 23% of respondents saying he intentionally helped the environment.

From this, it appears that intentionality depends to a large extent on whether the action is something to be condemned or praised, or in other words has an element of judgement in it.

This, basically, is your “intended and intentional action” reference.

It is not the same to use something intentionally than using it as intended. But when used as adjective the difference might not be so clear as with the adverb.