Ho fun is fresh rice noodles and chow fun is ho fun that has been stir-fried. The word 'chow' literally translates to 'stir fry' and the word 'fun' literally translates to 'noodles' but there are many ways to say noodles (mein, fun, etc) and in this case, the word 'fun' is referring to ho fun. The word ho fun is also used in dishes that use the ho fun noodles that are served in soups or stir-fried with gravy.