http://stackoverflow.com/questions/25448482/compare-two-lists-and-find-similar-data/25449454?noredirect=1#comment39710543_25449454

gistfile1.cs

public static IEnumerable<T1> FindSubsequence<T1, T2>(
      this IList<T1> first,
      IList<T2> second,
      Func<T1, T2, bool> matchPredicate)
  {
      T2 firstofsecond = second.FirstOrDefault();
      var locations = 
           first.Select((ele,index) => new { ele = ele, index = index})
            .Where(item => matchPredicate(item.ele,firstofsecond))
            .Select(item => item.index);
            
      foreach (int i in locations)
      {
          var subsequence = first.Skip(i).Take(second.Count);
          if (subsequence.Zip(second, matchPredicate).All(x => x))
              return subsequence;
      }
      return Enumerable.Empty<T1>();
  }

Optimized to not have to perform
var subsequence = first.Skip(i).Take(second.Count);
for the number of elements in first list.