The severity of a vulnerability is associated with system standards and the technical perspective of the system workflow. Severity examines whether the impact is severe or not. The severity level is less likely to change, while priority might differ.
Priority indicates how quickly a vulnerability should be fixed and eradicated from an application. It shows a sense of urgency for dealing with a vulnerability in your system, with priority one being the highest and five being the lowest.
Examples
A vulnerability that occurs in the basic functionality of the application, if it’s not fixed soon, will impact the business goal immediately. For example,
A P1S1 vulnerability means your website is at risk of being hacked anytime. We recommend that you make it your highest priority to fix these vulnerabilities immediately.
A vulnerability that occurs on the application's functionality that can be exploited by malicious attackers to access sensitive information on the application or server. The impact of S3P3 is relatively limited. For example:
Any vulnerabilities that are acceptable business risks to the organization/company. For example:
Things that can be used in conjunction with social engineering to cause a more severe impact on the target.