deceitfully/deceptively (definition/question of methods)

What are the technical differences between the two?

How are each applied and to what specifically?
(Mainly: Action [or situation] v. Object)

Heated debate going, more details later, thoughts please!
Thanks :]

Side note: I’m fairly convinced the former is nearly impossible to use in relation to anything.

Deceitfully is normally applied to someone’s actions or behavior, and means that they are acting in a way intended to deceive, almost always for bad, selfish motives. A liar or a con man acts deceitfully (but it would be odd to say that a conjurer is acting deceitfully, because although he intends to deceive you, it is not out of bad motives, does not harm you, and he generally does not hide the fact that he is deceiving you).
**
Deceptively** is normally used of things, not people, and means that the thing in question is likely to deceive you because it is actually different form how it appears at first glance. A deceptively difficult problem is one that looks likely to be quite easy, but proves to be quite difficult when you actually try to tackle it. It can be confusing, however, because in some contexts it can have two quite different, and almost opposite, implications. If someone says that something is, for example, “deceptively small,” they might mean it appears small, but is really not so small, or that it does not particularly appear to be small, but in reality it is small.

Deceitfully is usually used to modify verbs and deceptively is usually used to modify adjectives.

Why on earth would you think that? People often act deceitfully, and it is often worth pointing it out when they are.

Of course you could have found all this out very quickly and easily by using a dictionary (many free ones online). I am a fool for taking the time to answer you really.