Learning fine-grained distinctions between vocabulary items is a key challenge in learning a new language. For example, the noun wall'' has different lexical manifestations in Spanish -- pared'' refers to an indoor wall while muro'' refers to an outside wall. However, this variety of lexical distinction may not be obvious to non-native learners unless the distinction is explained in such a way. In this work, we present a method for automatically identifying fine-grained lexical distinctions, and extracting rules explaining these distinctions in a human- and machine-readable format. We confirm the quality of these extracted rules in a language learning setup for two languages, Spanish and Greek, where we use the rules to teach non-native speakers when to translate a given ambiguous word into its different possible translations.