Yeah I'm with you Toodoped. I don't believe that these roles/ranks are the same as alot of people here suggest. In my mind, they're three distinct positions. Acknowledged internally or otherwise.

Acting Boss - Obviously, this is a position of stewardship. In the old days I think this position was more temporary. Often created when the Official boss was in jail, infirm or otherwise incapacitated. In this day and age, when being boss brings so much heat. It's bad news to be the "named boss" so sometimes the Acting boss will stay Acting for a much longer time then necessary. Sometimes the Acting will truly become de facto, in which case it might develop into a Front Boss type of relationship. It really all depends. But most of the times the Official title is honoured.

Front Boss - By no means an official position. This happens for the same reasons that Acting Bosses keep Official Bosses "in power" even though they have relatively none. Because it preserves the status quo and it diverts attention way from the real leadership. This setup can happen in an Official/Acting relationship, when the Acting Boss' influence supersedes the boss'. These Front Bosses can be installed as well in the case of Natale/Merlino. Along with other circumstance where the Official Boss is emasculated.

Street Boss - Can be either a senior captain or in an official capacity a "captain's captain". In some of the more progressive families, this role/rank has surfaces in relatively modern times. In the case of the "senior captain" aspect it is a privileged captain who has come influential in some large way. A scion and pillar amongst his peers. This affords him a degree of reputation and power that rivals the typical three-tiered "Administration".

In a more concrete capacity, of a "captain's captain" it's a role where this "Street Boss" is put in charge of handling the regular captains of the family. In order to put some distance/ or a buffer between the "Administration" and the Captains themselves. This is usually done by rather large families with many captains.

The Street Boss position, whether it's official, unofficial, semi-official, or assumed is one that is relatively recent and has seemingly been adopted by the large more enterprising families that view it as a necessity to move away from tradition. We're talking about an organization with hundreds of members and thousands of associates. To think that a three-man Administration and tradition are enough to keep such a large group like that together without any divergence goes against common sense.

Obviously, there are many degrees of overlap between these three roles and it is often circumstantial, and shifts frequently it would seem. Only the basic time honored structure seems truly set in stone.