What is the difference between Functional Requirement and Non-Functional Requirement?

The Functional Requirement specifies how the system or application SHOULD DO where in
Non Functional Requirement it specifies how the system or application SHOULD BE.

Some functional Requirements are

• Authentication
• Business rules
• Historical Data
• Legal and Regulatory Requirements
• External Interfaces

Some Non-Functional Requirements are

• Performance
• Reliability
• Security
• Recovery
• Data Integrity
• Usability