Spelling is one things but some words actually have a slightly different meaning. The word momentarily for instance. Obviously there are the biggies like 'fag' and 'rubber'. I managed to avoid them for virtually the entire time I lived in USA. It was mostly ok, most of the time I could make myself understood, however speaking to foreign nationals whose first language was not English was just about impossible. It helps to know French because it meant I could muddle through with a little Spanish but thats it. Of course, the English I speak is the correct English. Not that Scottish interpretation Ya ken?