Guy,
Application letter and cover letter are same,just that the context of their uses can vary.
A letter of application typically provides detailed information on why you are qualified for the job you are applying for. It explains the reasons for your interest in the specific organization and identify your most relevant skills or experiences.
A cover letter is a motivational letter that serves as an introduction to the employer in order to catch the interest of the employer.
While cover letter can also mean an application letter ,it comes in different format and purpose .They are:
Invited cover letter which responds to a known job opening.
uninvited cover letter which inquires about possible positions
other uses of cover letters are loan application.
Hope ur satisfied.
Regards