Your resume is arguable the single most important part of the application process. A well-organized, relevant resume will set you up to get an interview, while a poor resume will get completely lost in the sea of applicants. This is a fairly modern concern, as job postings now get thousands of online applications a day.
Generally, a resume is much shorter in length compared to a CV, usually limited to one page. It is meant to be a very brief synopsis of your career and education history. Resumes should focus on measurable accomplishments rather than soft skills or listed responsibilities. Like a CV, resumes need to be updated, but those updates should be made form specific job to which you are applying.