A ™ is usually used to indicate an unregistered trademark. It is an informal notification that there is a public claim as a trademark.
An SM represents an unregistered service mark. It is also an informal notification that there is a public claim as a service mark.
The ® (the “‘R’ in a circle”) is a warning notice to advise the public that the mark is registered with the Federal government and their use provides legal benefits. This notice can be used only with registered marks. Use of a ® with any unregistered trademark may result in claims of fraud. Most other countries permit or recognize the use of the ® symbol to indicate that a trademark or service mark is registered in their respective trademark offices. However, you should check with local trademark attorneys in countries in which you are interested to ensure compliance with local laws.