how does an Officer's National cockade differ from an NCO's?
Good question. And remember everything dealing with these cockade's are generalities. There are exceptions to every single rule.
In general, there seemed to be several frequently seen trends. Officer Cockades are larger. Generally about 55 mm. They have a double ring on many. For example:
An enlisted cockade is smaller generally 48 mm. There is no metal ring attached. For example:
The Portapee NCO cockade is often the same size as the enlisted one at 48 mm but has a single ring.
Both single and double rings are attached making this a multiple piece cockade.
Some officer helmets are not multiple piece but rather one piece and have no rings. This is the same for some Portapee cockades but this is entirely state specific.
In addition, there is a difference in the size of the holes. Big holes accommodate M91 type posts while the small holes accommodate a smaller brad. most officer helmets have small holes until you get to the M15 type.
A few years ago James bought a salesman sample for Baden that showed all of the different sizes and shapes for that state. Perhaps we can get him to put a picture of that up.
While I am on a roll here are some pictures of the two different kinds of pearl rings. There are two kinds of pearl rings. Old style which were discontinued officially for many units in the 1895 pattern OR helmet. OR pickelhauben are often called "NCO pearl rings" in error. Every OR had them up until 1887 and some unit types retained the old style pearl ring right to the end. It is possibly an NCO but more probably an OR. If you have a 48mm cockade with a silver ring it could well be a Feldwebel. The Officer or private purchase pearl ring was the egg and dart variety.
I took several pictures from other members postings on the thread http://www.pickelhaubes.com/bb/viewtopic.php?f=9&t=7526" onclick="window.open(this.href);return false; because I am lazy. Perhaps Brian can dovetail this answer into that sticky.