To being with, the basic difference between CV and Resume is CV is British English and Resume is an American word for your career profile. Now, leaving the vocabulary aside, there are principle differences between the two and let us look at those differences.
A CV (Curriculum Vitae, which means the course of life in Latin) is an elaborate document which runs over two or more pages. It is your professional biography which speaks in detail about your achievements and accomplishments. CV covers not only your academics and career graph but also other accomplishments like publications, awards, honors etc. This document is organized chronologically and gives an overview of the individuals full career.
A resume is more or less a concise document which typically fits in a single page. It is argued that if your document is too long, people won't be interested to read it. Since it is specific to the particular job you are applying, the resume is tailored according to the position you are applying. The purpose of the resume is to make an individual stand out among the candidates.
To sum up, the three major differences between a CV and Resume are the length, purpose, and layout.