知道 and 认识，they can be used in many same situations.For example,you can say"我认识路（road）"or“我知道路”（means：I know the way.）But,they also have differences,you may say"我认识那个单词（word）"，but we seldm say"我知道那个单词".That is to say,"认识" emphasis on that"we know sth. or sb.,and we as well know what we know looks like and other informations about sth.or sb.",however,"知道" emphasis on that"we know sth. or sb.,but we may not know its appearance.".And in many circumstances,the usage of both words is only a traditional way we Chinese people say.