Given the confusion which Intel's practice of using the same processor family names for a variety of processors which differ in many ways, the processor number is a first step towards helping to minimize the confusion for PC users and buyers. However, because Intel uses so many different factors to determine where processors with similar features will be numbered in relation to each other, it's far from perfect. And, it won't help you decide which processor family to select from.
You'll still need to examine the specifications for processors with different processor numbers to determine exactly why Intel numbered them the way they did. It's likely that in some cases the reasons will be less obvious than in the examples I've chosen here. In selecting a processor, the best method for selecting a processor is likely to be this time-tested method: consider processor and system reviews and real-world performance tests. Then, compare the prices of the best-performing processors to the size of your budget.