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.
Using a functional resume format is beneficial when you have gaps in employment. The functional resume highlights honors and achievements more than work experience. It lists your skills and other attributes that make you a good employee at the top of the resume. It is important to fill the gaps in employment with experiences that helped you grow. Volunteer work, continuing education, and other projects you worked on during that time are all great options. Be sure to use a positive tone while describing the gaps in employment and be confident about them when interviewing later.