Resumes often serve as your initial contact with employers and are the most critical item in determining whether or not you will obtain an interview. The document is a brief "advertisement" of your skills, education, and relevant experience. You may need to have several versions of your resume, especially if you are seeking various positions. It should be specific to each type of job you are seeking; a general or generic resume gets far fewer interviews.
The primary purpose of a cover letter is to acquaint the prospective employer with your unique talents, experiences, and skills, and to request an interview to discuss employment possibilities. The cover letter should highlight your resume by identifying how you are qualified for the position and the reasons why it will be to the employer's advantage to hire you. It is valuable to state the reasons for your interest in that particular employer and the position.