Still a little confused as to the differences between WordPress.com free blogs, WordPress.org, and WordPress-platform custom websites? No problem—let’s break it down again: WordPress.com is a free and easy tool for creating your own quick blog, much like Google’s Blogger or Tumblr.
If you’ve always wanted to start blogging as a hobby, WordPress.com is a great place to start (creating a blog on its own domain; for example, http://yourblog.wordpress.com). WordPress without the “.com” on the whole is actually a web format, a structure for creating sites of various orientations, and a content management system.
WordPress.org is an endless array of support resources, including themes and plug-ins for customized WordPress websites on custom URLs. Note that there is no “official” support for WordPress.com (as with so many modern open-source CMSs).
But some of the support content available on WordPress.org can also be available for WordPress.com blog issues. So you can start by creating a free WordPress.com blog, get comfortable with the usability, controls, posting, and edits, then build a customized WordPress site from a broader availability of more editable themes, and then integrate the content from your original WordPress.com blog.
Both WordPress.com themes and WordPress.org themes for customized WordPress sites are similarly available for researching, choosing, and integrating for your blog (depending on which format you are using).
In either scenario, you can try out different themes and preview how they look with your content. The major difference occurs in the WordPress.org theme customization for your own site. In these cases the sky is the limit—you can have full cascading style sheets (CSS) editing options, add on any plug-ins you want (although some may be incompatible), and open up your site for additional functionality, such as eCommerce or forum.