Why do I get a low matching score in CV to JD matching but a good matching score in case of JD to CV matching?

Document match scoring depends on the no. of entities in a document and the matched entities with other documents wrt entities weightage. Generally, JDs have less no. of entities than the resume. Thus, a JD match to Resume has a higher score whereas the resume matching to the same document has a lower score. e.g. just consider a JD with 5 skills and a resume with 10 skills. So, when we match JD to resume, the skills have higher weightage but when we match resume to JD, the skills have less weightage.