NO.....
That is not how the ratings work.
Just look at this chart from novaks website and you will see that.
http://www.teamnovak.com/products/br...spec_chart.htm
There are several factors that will influence the rated KV of motor, The number of windings, type of windings, length of can are 3 of the bigger ones.
If I had to gues the whole .5 system was created to make it easier for the general rc population to know which motors were faster and slower. But this is just a guess on my part. I'm sure someone else will have more details.