Digital skills would focus on which tool to use (e.g., Twitter) and how to use it (e.g., how to tweet, retweet, use TweetDeck), while digital literacy would include in-depth questions: When would you use Twitter instead of a more private forum? Why would you use it for advocacy? Who puts themselves at risk when they do so?
I teach a CAD course and I always try and bridge the gap between skill and literacy. Which is the more important? Chicken or egg?