I was asked: what is the difference between merge and mix?
If I said “I will mix the colors”, is it the same as if I said “I will merge the colors”?
When should we use either verb?
You would not say that you merge the colors.
You also would not say that you mix into traffic.
I am not actually sure why, a quick dictionary search didn't make it clearer.
But I think you merge things when they keep their general form or configuration but blend together... where as you mix things when they get all out of order in the process.
Like with a deck of cards - merging two halves of the decks (shuffling -- we never actually say 'merge' about cards) -- mixing would be like dumping all the cards on the table and spreading them around with your hands.
Merge is less commonly used, btw - The two rivers merged into one, We merged the two businesses, there was an accident where the express lane merges into traffic.