WordPress.com is the hosted version of WordPress and WordPress.org is the self-hosted version.
WordPress.com is a free web hosting service that allows anyone to run a website without worrying about security, technical stuff, or managing site. WordPress.com has many limitations also. Your site will include advertising by default, and you'll have to use a branded domain name like yourdomain.wordpress.com. Also, WordPress themes and plugins are very limited.
On the other had, the self-hosted version of WordPress is very powerful, customisable, and isn't limited in any way. You have full control and ownership of your website and you are free to use and customise your website in any way you want.
In our Web Design with WordPress course you’ll learn how to use the self-hosted version of WordPress.