Background
I've been reading Pierre Hermé's Macaron cookbook, and his recipe for bitter chocolate macarons calls for "cacao pâte (or dark chocolate 100% cocoa)". I (naiively) thought that the only thing which was 100% cocoa was cocoa powder, so this was quite confusing to me. I told my friend about the recipe, and she told me to substitute the chocolate with cocoa powder, which seems like it might end badly!
Question
What is the difference between cocoa, cacao pâte, and 100% dark chocolate?
Research I've done
I've been reading about this for the past couple of hours, without finding any resources describing how they are different, though I've found many sites which describe each thing, though often using the exact same language, frustratingly!
At the moment, my guess is it's related to the amount of the different cocoa bean derivatives in each thing (from this comment on another question), but I'd like to be able to grok it, understand more deeply how they are different (especially if it goes beyond the proportions to the way they are processed or cooked for example). Any help you could provide in this would be greatly appreciated!