In spite of a great number of places worldwide English is spoken, still there are a lot of differences between 2 versions of the English language – e.g., American English vs British English vocabulary. Sometimes it is not that easy for an American English speaker to understand the language of a British English speaker. Luckily, the United States Department of State has developed a series of useful graphics aimed at assisting to clear the things up.
The imperial histories and powerful influence over the world by both, the United States of America and the United Kingdom of Great Britain, have significantly changed the English language, e.g., spreading the language all over the world resulted in different interpretations of it.
As an American or British English speaker, you have a great chance to learn something brand new here.