Elder Sign is a board game.
Elder Sign: Omens is an iOS app based on the board game, but with some distinct differences.
I would argue that the differences are significant enough that the two games should not be grouped under the same tag. Seeing this question which has the tag elder-sign on it, the same tag used for questions about the board game, was what originally prompted my question about the differences, since I was curious whether or not it was actually an exact copy.
It seems that it is not an exact copy, based on the answer I've received as well as the small amount I've played the iOS game, which I purchased after asking the question.
It also raises the question of whether or not questions about the app belong here, or on Gaming.SE.