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.
A resume is the representation of your professional self. It is a concise compilation of your educational and professional experience, as well as the skills that make you desirable for the workforce. It is what you use to sell your merit and skills to potential employers.