WordPress.com or WordPress.org?
WordPress.com is a super simple hosting platform which makes it easy for anyone to publish online. The WordPress.com software is hosted and maintained by the WordPress.com team so you don't have to worry about the added hastle of hosting your blog yourself.
It’s free and super easy to set up
All of the technical maintenance work is taken care of — Setup, upgrades, spam, backups, security, etc.
Your blog is on hundreds of servers, so it’ll always remain available, even under high traffic
Your content is backed up automatically
You can find like-minded bloggers using search facility
Your dashboard is secure (SSL) making it even safer to log in on shared networks
Limited, set themes (more are added daily) which you can personalise, but you cannot upload a custom theme
Some technical knowledge is required to personalise your blog
You can’t modify the PHP code behind your blog
More suited to small personal blogs
You can’t upload plugins
Note: There is a VIP program on WordPress.com for high-traffic and high-profile sites which allows you to run custom themes, custom PHP code, ad code, and WordPress plugins.
WordPress.org is free blogging software. With WordPress.org, you can install custom themes and plugins, run advertisements, edit the database and even modify the PHP code that powers your site. Anyone can download the software for free from wordpress.org, but it must be installed on your own web hosting package before it will work. Hosting your own WordPress.org software can be fun and rewarding, but it also places full responsibility on the blogger. If you mismanage your web hosting, you could lose your entire blog.
WordPress.org (self-hosted) Benefits
Ability to upload thousands of custom themes
Ability to upload plugins
No technical FTP, CSS or HMTL knowlegde required
Complete control over the appearance and functionality of your blog or website
WordPress.org (self-hosted) Cons
You must assign your own domain name
Creating and maintaining backups of your site requires an additional plugin
WordPress.org must be manually updated (single click) although update notifications are automatic.
WordPress.org is the website where the free WordPress software can be downloaded.
For no charge, WordPress.org provides downloadable blog software, mailing lists, community support forums, documentation, and free themes and plugins.
WordPress.com is different. You don’t have to download software or pay for hosting to use WordPress.com. Instead, you can focus on creating awesome content!
When you sign up for a WordPress.com blog, you’ll get a URL like andy.wordpress.com, or you can map a domain like myblog.com.
You don’t control the software or the database, so FTP and shell access are not included. For security and performance reasons, custom themes or plugins can’t be uploaded to WordPress.com.
However, a number of great premium (paid) upgrades are available — including Custom Design, which lets you customize the appearance of your site with CSS and take advantage of special web fonts.
For no charge, WordPress.com provides personal web hosting, unlimited database storage with redundancy and backups, automatic software upgrades, community support forums, multi-lingual administration and themes, real-time traffic stats, comment tracking, and other features not available anywhere else.
These features will always be free for blogs started on WordPress.com; if you ever find yourself being charged for these at WordPress.com, pinch yourself and wake up!
WordPress.com offers premium upgrades as a way to provide special features without forcing bloggers to host their blogs elsewhere. These upgrades are strictly optional. Basic blogs will always be free on WordPress.com and the basic services will continue to be upgraded with better features.