Dentro, Adentro Interchangeable?

Dentro, Adentro Interchangeable?
 

Is there a real difference in the usage of dentro and adentro. I thought that adentro implied movement, but in this question, there is no movement indicated.

(Duolingo-63) Write this in Spanish
The presidents are talking inside.

My answer, which was correct: Los presidentes hablan dentro.
Alternate correct answer: Los presidentes están hablando adentro.

The alternate correct answer is provided because 'adentro' may be used that way on this side of the pond (in Latin America). This is uncommon usage in Spain, so perhaps that is why both answers are acceptable.

In your other thread, about keeping your feelings inside, some will use 'adentro' instead of 'dentro' for the same reason. Regional usage drives which way it'll be said more often than not.

So, I would say that the two are not interchangeable, but it will certainly seem that way should you find yourself in Spain one week and in Mexico the next.

And I suppose there will be folks on both sides of the pond that will use the adverb the way they heard it used when they were young and won't relearn it when they move to a different region.

My :twocents:.

Thank you, Rusty. I guess I'm looking/hoping for absolutes, which don't exist. I suppose that this becomes less of a problem, as one gains confidence. The other thread was interesting, also.