The fact that an owner has a mark registered in one country gives no protection in another country. Some thought should be given to choosing a mark. Generally this is proved by surveys. Otherwise, descriptive marks can be registered only on the supplemental register. Roughly speaking, arbitrary and fanciful marks are the strongest, then suggestive marks, then descriptive marks.
Arbitrary marks use words, symbols, pictures etc.
Suggestive marks are those that require a bit of imagination, thought and perception to reach a conclusion as to the nature of the goods, for example Chicken Of The Sea or Coppertone sun tan oil. Descriptive marks describe the intended purpose, function or use of the goods, the size of the goods, the users of the goods, desirable characteristics of the goods, or the end effect upon the user. Marks that are laudatory are regarded as being descriptive, for example, Gold Medal flour or Blue Ribbon beer. Obviously, there is a significant subjective component to these categories. Obviously, there is no likelihood of confusion if the two marks are used in completely different commercial fields.