I was working on a document today where I wanted to include Trademarks (what can I say?) but didn't understand the difference between using the TM symbol and the R within a circle. So after some research:
A trademark includes any word, name, symbol, or device, or any combination used, or intended to be used, in commerce to identify and distinguish the goods of one manufacturer or seller from goods manufactured or sold by others, and to indicate the source of the goods. In short, a trademark is a brand name.
The federal registration symbol, the R enclosed within a circle, may be used once the mark is actually registered in the USPTO. Even though an application is pending, the registration symbol may not be used before the mark has actually become registered.
When you want to figure out if something has actually become registered try using the
Trademark Electronic Search System (TESS). (Don't government search engines get cute names?)
Other sites of interest while doing my research: