What does “infringement” mean?
Well, as in horseshoes and hand grenades, close counts in marks. When you own a mark, you not only can stop someone from later using the exact same mark to sell the same product or service, but you also can stop someone from later using a confusingly similar mark to sell even a similar product or service.
This means you have a zone of protection around your mark – your “mark turf.” How big that turf is depends on several things, such as how inherently distinctive your mark is and whether you picked a mark that is unlike any other mark being used to sell similar products and services.
Some marks have really narrow turf – essentially covering only exact matches of a mark for overlapping goods/services. Other marks have wide turf – the power to preclude even moderately similar marks used for even similar or complimentary goods/services.