The US, UK and EU all have government regulations about how much – or how little – cocoa an item can contain and still be considered “chocolate”, but those regulations are much stricter in Europe. In the UK, for instance, after Pladis reduced the amount of cocoa bean-derived ingredients in its McVitie’s Penguin and Club bars to below 20%, both treats were officially demoted from “chocolate” to “chocolate flavour”. In the US, the threshold is 15%, and low-cocoa items like the Unwrapped Mini Hearts can still be described as “chocolate candy”.

From the article, this is where the other answer probably got they link.