Legal Question in Business Law in California

If you are both in the same industry, your example would be a pretty clear infringement. The question would be who is infringing on whom. You say your company is "trademarked." That doesn't have legal meaning. If you mean it is a registered trademark with the U.S. Patent and Trademark Office, then they would be the infringer. But if neither of you has actually completed a PTO registration, it is more complicated. The mere use of "TM" or even using (R) when the mark is not registered, doesn't buy you much. Priorty in time is key along with proof of actual use in trade. So if they have been using it longer, you could be the infringer. If you want to file a lawsuit against them you really need to hire an attorney. Trademark infringement is not something for anyone who cares about their case to handle themselves.

Mr. McCormick is correct, and here are a few other possibly-worthwhile comments:

A similar brand name for the same kind of product may or may not infringe, depending upon the likelihood of marketplace confusion. If there are readily-noticed differences between the trademarks, or the products themselves are in different categories (like paint and perfume), or your markets are very widely separated ("Joe's Band & Grill" in Bangor, ME vs. same in Palm Springs, CA), it may be hard to show likelihood of confusion and a court would hesitate to enjoin the defendant from use of the mark.

Intellectual-property litigation is pretty expensive. A plaintiff may have to retain expert witnesses. It is better to settle.

Relief available to a successful plaintiff includes an injunction against the defendant's further use of the infringing mark and money damages for proven lost sales and profits. Unless you have suffered proven harm or face a threat of harm, neither the injunction nor the money damages is likely to reimburse your costs of suit if the infringement is only technical and minor.