What is the difference between an affiliate advertising network and a CPC advertising network?

As it says in the title really!

Affiliate advertising network is typically a CPA network, or cost per action -- wherein publishers are paid (and advertisers pay) only if the desired action set by the advertiser (e.g. newsletter signup, product purchase, download of ebook, leads) are accomplished. Examples include Commission Junction http://www.cj.com and Linkshare http://www.linkshare.com

A CPC advertising network is cost per click -- meaning publishers are paid (and advertisers pay) only if the ad is clicked, no matter how many impressions have been generated or whether the click led to a meaningful action