If Nintendo gave you 24 hours to make a short film about one of their games, what kind of YouTube classic would you create?
Because they don't count the CDi Zelda games, and because they count the repeatedly re-released Ocarina of Time twice, Nintendo promotes a worldview in which 17  Zelda games have been released in the past 25 years.
Here's a new trailer for the June-scheduled 3DS re-make of The Legend of Zelda: The Ocarina of Time. The graphics have been improved, though my memory already made them look as good as they appear in this new trailer.
The short answer: a lot. The long answer: a substantial amount, my dear, it really is quite noticeable.