Inexpert Opinion Here.
Comparing the written description of the Plymouth Rock, New Hampshire & Delaware from the American Standard of Perfection 2010 edition ... excluding the "good stuff" from the front of the book ... excluding history & economic qualities ... excluding color. Points awarded for which of the two parent breeds is described most similarly to the Delaware.
Males Only.
Size: New Hampshire & Delaware described identically. Point to NH.
Combs: NHs & Del described identically ... Point to NH.
Beaks: NH & Dels described identically ...Point NH
Face: All 3 very similar, but because the NH & Del are described identically in one important detail ... Point NH
Eyes: PR & Del described identically ... Point PR
Wattles: NH & Del described identically ... Point NH
Ear-Lobes: NH & Del described identically ... Point NH
Head: NH & Del described identically ... Point NH
(I think even I am getting the idea of what's going on here ... )
Neck: NH & Del nearly identical ... Point NH
Back: NH & Del described identically ... Point NH
Tail: each breed has a different tail angle, with the Del splitting the difference ... No Point
Wings: Del described more simply than the other two, but NH & Del wings should be the same size ... Point NH
Breast: NH & Del described identically ... Point NH
Body & Fluff: Hmmmm. The fluff of all 3 is described identically. For shape, the Del splits the difference between the longer PR and shorter NH ... No Point
Legs & Toes: One important similarity between NH & Dels ... Point NH
Plumage: Only described for the NH ... No Point
Conclusion: The size & shape of the male Delaware is supposed to be very much like the male New Hampshire, with the NH being slightly shorter and with a slightly higher tail than the Del. Otherwise, why bother?
As for the illustrations ... I'm not sure those are doing a very good job of telling the story of how the shapes of these three breeds should be different.
This has been a weird exercise for me.