Bell Helicopters Naming
Yes, essentially the model numbering system (not names as such) is, and was for the 204, 205, 206, 212, 222, 230 and 430, determined by the number of M/R blades. The 47 was determined by the year of certification. I'm sure your friendly Bell Tech. Rep. can expliain it in more detail - the methodology Bell used was on their website but it's now been taken down.
The current Bell models are 206L4, 407, 412 and 429. A completely new design is in the works and is presently known only as 'Magellan', I suppose the speculation can now start regarding it's model number.