Headscan, you are right.
Basically Necks or Capes are the pelt of the rooster from the head to the lower back of the bird. Near the head, the feathers are tiny, John Howard carries around a bag of long #28 /#32 hackles from some of his birds. Near the bottom of a neck, their feathers are large and used mostly on streamers or as tails and beards etc. The long streamers that Dave and I tie usually have wings created from these feathers. The nice thing about necks is that they have a large variety of hackle sizes. A good cape will have #20 - #6 dry fly hackle. There are people who claim the Necks to be better quality hackle, and in a lot of cases they are. The saddles are opt to have more webbing present.
Saddles are the pelts that you see with the very long feathers, sometimes 15 or more inches. One nice thing about saddles is that you can tie 7-10 flies from a single feather, but the biggest disadvantage is that the selection of sizes is minimal. you will normally have a saddle that ties 2 or 3 sizes with a few feathers that will tie outside that range. ie a saddle that has #10 -#14 sized hackles and a few #8 and a few #16. if you only tie in that range, a saddle is a good choice.
This holds for genetic hackles that are of dry fly quality. Indian, Chinese and domestic capes may have some feathers usable for dries, but they are often soft, short and difficult to work with for that purpose.
Hope that helps