There's and excellent comparison of wordpress.COM and wordpress.ORG differences prepared by Staff at the following support documentation link.
WordPress.com vs. WordPress.org
WordPress.com is a hosted blog service. You do not have to download software, pay for hosting or manage a web server. WordPress.com does not permit uploading themes or plugins. WordPress.org is free software. You can install themes and plugins, run ads, and edit the database. http://support.wordpress.com/com-vs-org/
This is the link to the support documentation entry re: types of blogs allowed and NOT allowed at wordpress.com. Please take note of this particular section posted below:
Affiliate marketing blogs: Blogs with the primary purpose of driving traffic to affiliate programs and get-rich-quick schemes (“Make six figures from home!!”, “20 easy steps to top profits!!”, etc). This includes multi-level marketing (MLM) blogs and pyramid schemes. To be clear, people writing their own original book, movie or game reviews and linking them to Amazon, or people linking to their own products on Etsy do NOT fall into this category.http://en.wordpress.com/types-of-blogs/
It's also important to know that wordpress.com blogs cannot be equiped for ecommerce. Those with free blogs being free hosted by wordpress.com are restricted when it comes to advertising. . Please see here > http://en.support.wordpress.com/advertising/ There are also code restrictions which can be viewed here. > http://en.support.wordpress.com/code/ In addition the ToS disallows wordpress.com blogs being used to drive traffic to third party sites.
Provided we are selling ONLY what we ourselves create and not retailing or retailing goods or services created by others then we can use contact forms and/or PayPal donation buttons. Please see: