Google Adsense VS Google Adwords

The differences between Google AdSense and Google AdWords for Blog owner are :

• Google AdSense is a program to put Google ads on your blogs. Google AdSense will give blog owners revenue when the visitors click the ads
• Google AdWords is a program that can be used by blog owners to advertise their blogs

So which one should blog owners use ? both, blog owners should use Google AdSense to get money and use Google AdWords to drive traffic to their blogs.