Translation is often thought of as a one-to-one exchange from one language to another. It’s often a literal transfer of meaning from one language to the next. It works best for technical texts, user guides, FAQs, online help and other straightforward content, generic content. It does not work well for creative content such as taglines.  Transcreation, on the other hand, is a creative adaptation process from one language (culture) to the next (culture) where the cultural knowledge of your translator comes into play. Imagery, cultural references, jokes and idioms all need to change. A phrase in one language, such as ‘take it with a grain of salt’, might not have an equivalent in another language. Also, we use a lot of baseball phrases like ‘touch base’, and another culture may not care about baseball or understand the references.  (Note that not all translators are great at transcreation. This requires a lot more research and craft).  You also need to know about native or in-country copywriting. You should consider this when the content needs to be completely local, or if the transcreation process is more work than just starting over and creating something very specific to your target market.