Difference between functional and non-functional requirements

Functional Requirements: It places the proposed system at the centre of focus, and provide a prioritised list of capabilities the system must demonstrate in order to satisfy the business and user requirements.

Non-Functional Requirements: It refers to needs that must be fulfilled related to things. They do not deal with the actual functionality of the system, but represents key project success factors nevertheless. List of Non-functional requirements are
user interface,
access security
Availability
Robustness
System Failure
Integration
Migration
Documentation
Installability.
Maintainability
Portability
Reliability
Scalability
Multiple Environment Support
Extensibility
Reuse
Operability
Privacy
Security.