WordPress and Tumblr both seem to offer beginning bloggers an easy entrypoint  into the blogsphere; however, upon deeper reflection, one can see that there are more differences than similarities.

• WordPress seems to attract people who like the written word.  Photos and videos are supported and used by WordPress bloggers, but one gets the impression that these are supplements to the written blog.  Some blogs even seem to eschew  pictures and video, offering word only posts. Tumblr on the other hand, seems to attract people who want to communicate primarily through photos and videos.  Often, the images posted are followed by only short, twitter-like explanations of the posting.
• Tumblr focuses on attracting visual creative types.    With it’s tagline, “follow the world’s creators”, its target audience is narrower and more clearly delinated than WordPress.  Just showing up at its homepage plunges the visitor into a plethora of overwhelming visual stimulation which one does not find on the “plain Jane” WordPress homepage.
• WordPress allows for more customization.  Tumblr’s simplicity, while good for beginning bloggers, does not necessarily lend itself well to the complex editing and features that more advanced users may desire.  By paying for the stand alone version of WordPress you can upgrade, create your own URL, and even add eCommerce functionality if you want avoid “starving artist” status. 

In summary, Tumblr is a better platform for visual, creative types who are just beginning to blog or who favor a simple, easy-to-use interface to exhibit their creative works.  WordPress is a better platform for those focused on written expression or for those who want to exert more technical control over their blog.  Upgrading to the stand alone version of WorkPress, allows additional control and provides a growth path for those who have outgrown the free versions of WordPress and Tumblr.