The panino con capocollo di Calabria is the same Calabrian cured neck read through its protected denomination, which is a tighter and more specific thing than the generic spiced version. The denomination fixes what the meat may be: pork neck from defined breeds, salted, pressed under a weight to compact the muscle, rubbed with wine and the region's chilli, cased in natural gut, and aged for a set minimum before it can carry the name. What defines the sandwich is that controlled consistency. The slice is firm and uniform, the fat well distributed, the chilli present but disciplined rather than aggressive, and the bite is the same from one producer's stick to the next in a way the unregulated kitchen version is not.
The craft is letting that regularity do the work and not overcomplicating around it. A denominated capocollo is sliced thin and even, the uniform marbling meaning every round carries the same ratio of lean to soft fat, so the sandwich does not need building up to compensate for a thin or fatty patch. The bread is a plain crusted roll, chosen neutral so the cure's measured spice and the clean pork flavour come through undisturbed. The classic build adds nothing at all, on the principle that a protected cure is sold as a finished product and a panino is the simplest honest frame for it; where anything joins, it is a thread of olive oil to carry the slice or a mild fresh cheese to round the chilli, never a second cured meat or an acid sharp enough to fight the regulated balance. The discipline of the denomination is mirrored by the discipline of the sandwich.
The variations are mostly about where on the ageing scale the capocollo is taken and what, if anything, is allowed alongside it: the younger, softer slice eaten plain, the longer-aged stick that is firmer and more concentrated, the pairing with a local pecorino. The more chilli-forward street reading and the cured-neck traditions of Martina Franca, Norcia, and Tuscany are each a different cure with a different logic. Each is one cured meat given its bread, and each deserves its own article rather than being crowded in here.