Let's start with the purpose of writing a resume; so simple but still true:

To get you a job interview

Without the job interview? No offer and no job. So it all starts with a compelling and convincing resume. 

What is the difference between resume and CV? The CV comes from Latin and comes from curriculum vitae. Translated to English: course of life. This document is typically five to ten pages so obviously not a great idea to use when you introduce yourself as an applicant or candidate to a new company.

In today's digital world where everything moves faster than ever, no HR Manager, no hiring manager, no recruiter will have time to spend more than 10-15 seconds on your resume. 

This is where the resume comes in. Resume is a French word for summary. So simply put, the resume is a summary of your CV. A one or max two page document that highlights your professional background.  

Check out the link below that lists some great points how to shorten your resume. If you are an executive with 15-20 years of experience, use two pages. If you are on your first or second job, one page should be more than enough.