This is a very commonly asked question, so, to keep it simple. One is limited, the other is not. One is free, the other is not. WordPress.com is a version of WordPress that is hosted by Automattic, the development team behind WordPress. WordPress.org is often referred to the self-hosted version of WordPress. These two are very similar. But there are a few differences that you need to be aware of before you finally get down to work on your blog.
WordPress.com is the safest way. There are a lot of mechanisms in place to make sure that you don’t accidentally break it or prevent it from working the way it was intended to.
If you want to take your blog past the hobby stage, you should just start out with a self-hosted site.
You can move a WordPress.com hosted site to a self-hosted site later on. However, presuming that you might consider starting with a WordPress.com site and moving to a self-hosted site later on, it’s better if you just start out with a self-hosted site.
That means, if you are comfortable living within the limitations of WordPress.com, and you want to never have to deal with the technical details of a blog, then a WordPress.com hosted blog is maybe all you need.
WordPress.com is great if you are looking to keep an online journal or for small clubs and the like. Due to the fact that you are reading this site, if you’re interested in making a business out of your blog. On that note, at some point in the future you will end up with a WordPress.org website.
The initially-free option of WordPress.com might actually result in higher costs down the road. After you start piling on extra fees for a custom domain, ad removal, extra storage space, plus the ability to use custom CSS in your blog design, you really don’t save much, if any, money on WordPress.com, and you have to deal with its limitations.
WordPress.org is the version of WordPress which you have to host yourself. This means if you use wordpress.org, you’ll have to go out and find a web hosting company to host your blog. In the result of this you may have to pay for services before you even hit Publish on your fist post.
WordPress.org is an open source and a self-regulating community project. The base CMS is free, and so are many of the thousands of plugins available at wordpress.org/plugins/. To be short, the possibilities are endless. There are very few limits you might face with WordPress when trying to accomplish what you’d like to do with a website.
Anyway, the WordPress.org software comes with a learning curve. You will need some technical knowledge to set up a site using it. It’s not impossible to learn though. In many cases, it acts like an accessible learning tool to those who want to get into the web development arena.
But in short, WordPress is awesome in general, and its awesomeness is growing.
Hope this article was clear and helpful enough!