Vulnerability Assessment tests are a series of tests performed on a system to identify the vulnerability of the system. This is a Security Assessment conducted to understand the vulnerabilities and by this process the vulnerabilities are identified and exposed to the security experts who in turn are able to quantify and priorities such vulnerabilities.
A Vulnerability Assessment is a simpler exercise than a Penetration Test. It does not actually simulate an attack or attempt to exploit vulnerabilities found. It notes all vulnerabilities and security issues detected and the results are delivered in a final report.