the difference is chicagos structure, rules, tradition, etc. came all later than the other mafia families did. the american mafia became the sophisticated organization around the 1930s while the chicago mob did around the time of accardo if im not wrong.
this meant also getting made, keeping things low profile and being italian and stuff. around capones time things wherent as organized as it was with accardo.

"...Accardo has more brains for breakfast than Al Capone ever had all day." -Paul Ricca