Wordpress is powered by a company Automatic and wordpress.com is used for commercial profit websites. Commercial profit websites are the sites that are used to earn valuable profit from your website. This platform is used to host a website for you and it works more like a website builder. For example HostGator website builder Square space builders etc.
In the early stages, wordpress.com was very simple for its users. Even a person can use it that has no deep knowledge of WordPress. The reason is that wordpress.com provides the all built-in features and the entire hosting domain for their users. The people just sign up for their account and can start building your site.
On the other hand, wordpress.com comes with some severe problems. The common problem of using wordpress.com is that when you host your website on it you will have to use the wordpress.com URL attached to your domain name. You cannot use your own domain name without using the worpress.com domain.
For example, when I started my first article I had my own domain name like www.xyz.wordpress.com I have to use this complete domain name when hosting a domain on it. When my article started more traffic I realized that I needed my own domain instead of using the wordpress.com domain. I purchased hosting from a Webhosting company and transfer my WordPress site to it and it allowed me to use my own domain name.
The difference between wordpress.com vs wordpress.org is that wordpress.com uses the domain name and worppress.org does not need a domain name. Both have their own uses and functionalities.