WordPress.org is a website that is dedicated to distribution and help with the opensource WordPress content management system which powers millions of websites. My website monyhan.me is powered by the WordPress software which hosted on a server that I control. The responsibility of maintaining the sites front end is all mine. The backend (the hardware) is taken care of by the hosting company. There is a third kind ware you maintain the hardware and the software, and security. This is not what anyone without millions of dollars to spend does.
WordPress.com is a managed web-hosting provider, with over 455 millions sites . They manage the hardware, the software, and the databases. There is no need to be concerned with anything but your content. With this there are some limitations. Many of these limitations can be overcome by paying them, or paying more.
A basic WordPress.com site is free but you have to put up with many restrictions like having the domain “[email protected]”, and other restrictions. Other hosting plans start at $4 per month, to $45 per month for the eBusiness Plan. There are concierge plans that aren’t even list on the website. I would image the price is extraordinary! WordPress.com Plans