There's a question with answers detailing the difference between pure cocoa powder and chocolate; it boils down to the 'raw' cocoa powder being a very ungrateful, bitter substance difficult to use without making the results taste terrible. It takes quite a bit of processing to be turned into chocolate; the difference is obvious.
Still, there are nice friendly and tasty 'instant' cocoa granulates that make quite delicious drinks very easily, "Just add hot milk".
And then there's instant drinking chocolate, "Just add hot milk".
What's the difference between the two? Is it just naming/branding technicality or are they two different drinks?