What is the difference between the different types of sausages, salamies, and pepperonies?
The kinds of meat used, the ratio of meat to fat, the kinds of seasonings used, whether smoked or fresh , whether it's cured or not, if cured, how, aged or not, how long, the coarseness of the grind of the meat.
Ingredients, and curing process (or lack thereof)
Ingredients and taste.
The differences are in the spices added, the meat they're made with, the method they're cured with and the resulting flavours.
The ingredients and how they are made.
The type of meat(s) used, the part of the animal the meat(s) came from, the amount and type of fillers (fat content. spices, herbs, bulking agents), how they are manufactured, how long and how they are aged/cured.