Unwittingly Vs unintentionally

[david11]

I see all the examples for the uses of the word "unwittingly", to mean "unintentionally", appear to be completely interchangeable with the word "unintentionally".

I am told that no two words can be completely same! Is there in any context that both can not be interchanged?

 

[Grumpy]

"Unwittingly" specifically means not knowing about something, while "unintentionally" specifically means that the action was not deliberate.
Let's suppose that I am trying to hammer a nail into a piece of wood. I miss the nail, and hit my thumb with the hammer. I certainly did this unintentionally - but I did not do it unwittingly, as I certainly knew what the consequences of hitting my thumb with the hammer might be!