The difference between the two symbols ® and TM is whether the trademark has been registered with the federal government. A mark with a TM signifies a mark that hasn’t been registered; the ® symbol can only be used with a trademark that has been registered.
There is no requirement that a trademark be registered. In fact, just by using your trademark in connection with the sale of your products or services, you do create some rights in the trademark. However, those rights aren’t as great as the ones you get when you register your trademark.
Registering your trademark gives the public constructive notice that you claim ownership in the mark – in other words, a competitor is deemed to know, even if they don’t actually know, that you own the trademark. When your mark is registered and you’ve used the ® symbol, you can also obtain damages from the person that was copying your mark.
Second, registration creates a presumption that you have senior or superior rights to the mark over anyone else who uses the same mark.
Third, registration allows you to bring a federal lawsuit based on federal law against anyone who may copy your trademark. Without registration, you would be forced to rely on a patchwork of different laws in each state to assert your trademark rights.
Fourth, registration provides a basis for you to broaden your trademark protection to other countries. With federal registration, you can file one fairly simple application that leads to protection in many countries around the world.
Finally, if you are dealing with a product that someone might copy overseas and ship into the US, registration helps your prevent importation of infringing gods.
Without registration, none of these rights are available. Instead, the rights you have in the trademark depend primarily on the law of the state in which you are using the trademark, which, if you sell in several states, would mean you have to know the trademark law of all those states.
Once you have registered your mark, you still have to be careful about how you use it. Applying it over-zealously or inappropriately could be considered fraud and provide a basis for invalidating your mark as to some uses or even completely. So, if you haven’t registered your mark with the federal government, use the TM symbol. After you’ve filed an application and have actually gotten a certificate of registration, you can begin using the ® mark.