When I was training as a language teacher we were told that, very often, students have more difficulty not with a feature of a language that is very different from their own but with one that is only a little different. The words that don't sound anything like English ones are easier to get right than the ones that sound somewhat like English but actually have a different meaning. English and American English are just different enough to cause problems in that way.
NFAH commented recently on the phrase "Every little helps" and how she feels it really should have the word "bit" added to the phrase - "Every little bit helps." After reading on another blog how the German phrase "jedes bisschen hilft" translates as "Every little helps", I wonder if this is a phrase that has lingered on in our language since the days of the Vikings. These kinds of phrases can stop you in your tracks a moment, but when push comes to shove they are still comprehensible.
Miss Chicago, on the other hand, just commented on British understatement, specifically in regard to Marks & Spencers Rich Tea Cream Fingers (whatever they are!) which are advertised as "Really rather good." No missing words here. However, the statement "really rather good" sounds far less enthusiastic to an American than to a Brit.
When I was applying to graduate school in the United States, I went back to my alma mater and asked my tutor if she would mind writing me a reference, (knowing full well that she would NEVER have written me a recommendation for a place on a Master's degree course in the UK.) I explained where I wanted to go and why, and she assured me that she would write me a good reference. In fact, she explained, she had learned through bitter experience exactly how to write references for American universities.
She had once been asked to write a reference for someone for a position at an Ivy League college. The candidate was over qualified for the position, but wanted the opportunity to work at an American university for a while, and particularly an Ivy League one. She not only did not get the post but discovered that the man who was hired had vastly inferior qualifications and experience. So she did the American thing and sued. She won her case and was awarded compensation, but not the job. It turned out that the American hiring committee had interpreted what would have been considered a glowing reference in the UK as somewhat cool and not very enthusiastic. So my tutor assured me that she knew exactly what to write to get me accepted, hinting that by her standards it would be not exactly a work of fiction but certainly one-sided.
There are people like Lynneguist who base their profession on the fact that English and American are not really the same language. Most of the time the differences are insignificant, or easily understood. Occasionally however, phrases like "Every little helps", remind me that even though I've been here 25 years and feel very American I did not grow up here