DBA?

Data comes from http://www.indeed.com/salary

I do not really understand what is the differece between DBA and DB developer, it sounds like the DB developer develops the Database, defines tables, writing SPs,functions, triggers;and DBA runs/maintains them. But why DBA earns more than DB developer?

I should be a DBA. Sql is my most favorite language, and it is far from UI so no picky customers at some points. Plus it probably is a good career choice for elder guys/girls, LOL. I actually thought to be a DBA when I was 24, and my friend said no, nobody wants to hire a young DBA. But it seems to be the time now:)