As an important yet intricate linguistic feature in English language, synonymy poses a great challenge for second language learners. Using the 100 million-word British National Corpus (BNC) as data and the software Sketch Engine (SkE) as an analyzing tool, this article compares the usage of "learn" and "acquire" used in natural discourse by conducting the analysis of concordance, collocation, word sketches and sketch difference. The results show that different functions of SkE can make different contributions to the discrimination of "learn" and "acquire". Pedagogical implications are discussed when the results are introduced into the classroom.