This sort of thing has long been a sore spot for me, and in the past I have stopped buying brands because of it...
Whether or not you like Cuban Cigars, Habanos SA did do something right imho... they established a standard set of vitolas, and all of the cigars coming out of Cuba adhere to the standards...
The Vitola de Galera (Factory Name) list is here:
http://cubancigarwebsite.com/list-factorynames.aspx
(It is too long to cut and paste)
There is also a Vitola de Salida which is a market name, which can be different, and is the name that each brand gives to the cigar (the can be the same as the VdG)
For example:
The Cohiba Lancero: The Vitola de Galara (Factory size) is a Laguito No. 1, and the Vitola de Salida (Market Name) is Lancero
RyJ Churchill: VdG - Julieta No. 2, VdS - Churchill
Look around the site a bit, and it may become clearer than I could explain it here in my beer-fueled haze...