There is a big difference between the two. The thesis category of ancient literature is far greater than that of ancient literary theory. It can be said that ancient literature contains ancient literary theory, which is a branch of literature. The essence of ancient literary criticism is literary criticism. Ancient poetry theory, ci theory, literary criticism, preface and postscript of anthology, literary criticism, etc. They all belong to ancient literary theories, such as Poetry, Wen Xin Diao Long and Ci Hua on Earth.