Difference between WordPress.com and .org is where the software is hosted. You log into WordPress.com hosting server to create the website. But with WordPress.org you can upload the software to your own hosting server account.
Is a free bloging system but its not uploading to your server. It is best used if you want to get content information out on the web, but it is limit on themes and you cannot add extra software / plugins with it. Also you need to login to their server to make changes.
Is free too, but is best to use it for a web site, it can be uploaded by a web designer to your site and they can add extra software / plug-ins like shop cart, slideshow, mobile pack, forms, and video. In fact there are thousands plug-ins to choose from. You can choose from a greater range of themes & can pick a theme to suit your business needs.
We can help on: How to use WordPress and website design. Create a website in WordPress, how to install WordPress. We are a Irish web training service and we cover Dublin, Wicklow and Wexford areas.