AMD Code name questions, whats the difference?

Hopefully an easy question for yall, what is the difference between all the AMD code names, such as San Diego, Clawhammer, Venice, and so on. When looking at the specs all the cache sizes seem to be the same, as do the stock frequencies. From what I understand the Code Name is the type of Core, but other than that im confused as to what their differences are, and if they have any notable performance difference in any commonly used apps (not stuff like benchmarks). Thanks in advance!

 

Google?
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2178&p=2