[DaBear]

I would assume the bowl mouth refers to the width of the bowl, the pipe itself is teardrop in shape, so I would assume the bowl would be similar to keep a semi constant thickness on the bowl. Don't take my word on that, could be wrong.

Nomenclature is referring to the markings on the pipe itself(ie, the "Pimpernel Blue" stamp on the side of the pipe in the first picture). Most manufacturers put something to that effect on the pipe to make it known at least the series for the pipe, and typically the maker's name as well(ie, Savinelli typically does not stamp their pipes with "Savinelli" but the do stamp them with the series/line).
tl;dr, its just showing what the pipe is