Samsung vs. Apple feels like the Yankees vs. Red Socks or insert your favorite sports teams. Instead of rooting for your favorite sports team, you're rooting for your favorite phone manufacturer or tech company.
Also, shipped vs. sold makes any time a company brags on how many phones they shipped very misleading. Many companies are famous for channel stuffing to get the PR boost and to "fake it til they make it".
In Samsung's case, the sell through rate is probably pretty high, but still nowhere near as accurate as when Apple says how many devices they sold (as Apple only has 5 days inventory at any given time, Samsung probably maintains months of inventory).