Official Answer: Quest Stage == Quest Card
Caleb by e-mail wrote:
you’re asking if there is a significant difference between the term ’quest stage’ vs ‘quest card’ and the answer is ’no.’ Those terms are used interchangeably. The number of quest stages in play is equal to the number of quest cards in play.
I was hoping there wouldn't be inconsistency within a single set (I understand how words from 2010 and 2015 could end up inconsistent).