I have had many customers buy a theme, only to find out that their WordPress.com account did not allow for premium themes to be uploaded to their dashboard. The difference between a WordPress.com website and a self hosted WordPress.org website is that WordPress.com is owned and hosted by Automattic. The company Automattic are the authors of the free and open source content management system named WordPress. They write and maintain an amazing piece of software, and give it away for free to the world. Automattic monetizes their free code through their website, WordPress.com, by offering free website hosting with ads, or premium hosting accounts for a monthly payment. Their platform and support service is excellent, and second to none in my opinion.
Alternatively, you could take WordPress’ free open source code at WordPress.org, and install it on your own web server, and own it yourself. Many web hosting companies like Bluehost, WP Engine, and Liquid Web, offer specialized hosting for WordPress, which make it easy for you to buy hosting with WordPress already installed and optimized.
The Big Difference
The big difference between WordPress.com and WordPress.org is that a self hosted WordPress.org site installed on your own server gives you the freedom to install a myriad or premium themes and plugins from market places like Theme Forest, Creative Market, and the Mojo Marketplace. However, the downside is that you have to maintain and manage your WordPress site, and any plugin or theme conflicts that come your way. This is where the advantage of a paid WordPress.com account comes in. Their plugin and theme environment is more controlled and streamlined, but you can be assured that everything will work well, and if you have any problems, their customer support is amazing. You might pay a little more than a self hosted site, but you will get ease of use and save yourself a lot of time. As an added plus, their business plan now allows you to upload premium themes and plugins.
You can make either account work for your purposes. So go ahead and get started building your website.