Actually I'm bit confused because there is very narrow difference between these all. Please anyone explain me precisely. Do share your Knowledge and share some useful precise material if availabe. Thanks!
I'd always assumed that the only difference between a CV and a resume was that the former was used in British English, while the latter was US English. However, there are a number of websites which cover this (see links below) and they all suggest that the main difference is length. A resume will rarely be longer than 1 page while a CV is longer. For most roles a CV will be 2-4 pages, but an academic CV can run to many pages and give details of roles, responsibilities, publications, awards, etc.
The cover letter is quite different. This is, as the name suggests, a letter sent with your CV, and is an opportunity to personalise your application. It would normally include details of why you are interested in a position and why you should be considered for the position.
I'm just an academic and don't work in HR, but I hope this helps.
The resume is a short version of the CV and it is used mostly in application for jobs with the assumption that Human Resources department prefers short job applications. The CV is used mostly in the academia, and designed to present faculty's achievement in full, and this contributes to faculty promotion process. The cover letter is a way to approach a journal editor when sending an article for publication. The cover letter explains in brief what is the article all about.
CV is explaining someone’s course of life, especially those most relevant to the realm of academia. Generally, it is providing complete information about academic qualification, work history, skills, projects, publications, achievements, and awards. The resume is the short version of CV and it is mostly used in applications for jobs. Here's a nice article discussing the difference between CV and resume.