WordPress.com vs. WordPress.org

The distinction between WordPress.com and WordPress.org can cause some confusion for some people.

Let’s clear it up. WordPress.com is brought to you by some of the same folks who work on WordPress, the open source blogging software.

WordPress.com utilizes the same WordPress software which you can download at WordPress.org.

With WordPress.com the hosting and managing of the software is taken care of by the team here at Automattic.

With WordPress.org you need to install the software on your own server or with a 3rd party provider.

WordPress.org is a free blogging software. With WordPress.org, you can install themes and plugins, run advertisements, edit the database and even modify the PHP source code. WordPress.org is the home of this software. Anyone can download the software for free but it must be installed on a web server before it will work. (…)

For no charge, WordPress.org provides downloadable blog software, community mailing lists, community support forums, documentation, and free themes and plugins.

WordPress.com is different. You do not have to download software, pay for hosting or manage a web server. When you sign up for a WordPress.com blog, you will get a URL like “andy.wordpress.com” or you can map a domain so your blog is available at “example.com” without the “.wordpress.com” portion.  You do not control the software or the database; FTP and shell access are not included. WordPress.com is based on a multi-user version of the WordPress software which does not permit uploading of PHP themes or plugins (although many popular plugins are built into WordPress.com ).  Popular javascript embeds such as YouTube are supported, but for security reasons some of the lesser known embed codes will be stripped out.  CSS is also restricted by default for security reasons, but you can purchase a paid upgrade to gain the ability for full CSS editing.  (…)

Source: en.support.wordpress.com/com-vs-org/