There are two theories of Chicago:

1) Boss, Under, Consig, streetboss, Capo, lieutenants, soldiers, associates

2) Three large groups with it's own boss and under, under them are regular members and group leaders, and under that nucleus of traditional italian leadership are the associates/soldiers.

Detroit has the same hierarchy as 1) only with counselor emeritus or semi-retired members who are still involved with the administration direct.

Each network that matured did so its own way throughout the century based on its surroundings. NY had 5 organizations by the 1920's with close proximinity to Boston, RI, NJ, Pennslyvania and Alabama, so naturally there is a closely shared protocol that continues today, which may be why you heard so many members refer to the group as cosa nostra, whereas in Chicago you heard outfit.

While all American LCN groups past and present had a similar hierarchy and structure, outside of NY it seems to have been more horizontal in structure with members involved in various ventures. Whereas in NY there is more emphasis on rank and trickle up economics, and that have had to do with the influx of membership that accelerated during the 1920's. Most Mafia organizations in Sicily rarely amounted to more than 10 members each, Palermo groups were somewhat larger in the 60's range, but by the 1920's, informants estimated that there were 3000 members in NY alone. That number is, by all accounts, grossly inflated, but even half that number would be a group number split between 5 networks. That may be why a more rigid hierarchy is needed in NY than in other places.