Of the three features you cite, how can you tell the pylons look thinner when we only see the 4" from the side? And how is the very odd shape of the bottom of the saucer any different from the 33" at that distance or the 11' with the random mattes that cut into it every once in a while? Only the neck appears longer and even that could be reproduced with a strange matte cutout. I suspect that if the scene with the 4" model was mixed in with the 18" AMT, 11' and 33" from the entire series into a collage that most people would be hard pressed to find it. Of course, they are supposed to be the same ship. However the 4" and the 18" AMT are meant to be and only seen at a distance where you can't discern details to distinguish them from the 11' and 33" (which can and are seen up close). So in the example where you say that details cannot be seen on the 4" we have an example of the 11' where the details also cannot be seen when viewed from a similar distance. And since we see strange matting issues on the 11' it is also possible that the 4" can have them too resulting in the odd shape of the primary hull and neck. I see no problem with the Constellation having a design that is identical to the 18" AMT model (and not the 11') since that is what we see up close. If they really wanted to convey that the Constellation was the same design they could've done something similar to "The Tholian Web" or "The Omega Glory" and re-used shots of the Enterprise from a distance or at an angle where the registry isn't visible. But they didn't. I see the 4 filming models to be the same ship that can change between configurations since they all appeared on film. However the drawings, or more specifically the Jeffries illustration from "The Enterprise Incident" is not a filming model nor is it accurate to a filming model. We don't have footage of this version of the ship flying around in space. But I don't dismiss it as not the Enterprise though. I would honor it as a version of the Enterprise that came before "The Cage" in-universe. I certainly wouldn't call it a mistake, IMHO.