Gangster And Mafia

What's the difference between Mafia and Gangster?
They may have a similiar history. But nowadays, Mafia clan is much bigger than Gangster team and has a kind of structure of organization. They do the bad things underground and of course, undercover. Like... we couldn't see what they do, what they've done, who they've killed, or where's the money come from. From the outside, they may look-like an ordinary super-rich bussinessmen. Mostly, Mafia clan has a kind of connection with the police or goverment so they don't have to worry about things.. They rule the city. No. They are the rule.

Gangster? Is a bunch of people, who do bad things and shown. People know what they do and what they've done. If there's a risky thing to do, Mafia Clan'll paid a Gang to do that job for them. Since Mafia wants to stay clean and doesn't want to play with the risks.