What’s the difference between UI design and UX design?

These are the Elements of UX according to Jesse James Garrett:

1. Strategy – user and business objectives
2. Scope – content and functional requirements
3. Structure – Information Architecture and Interaction Design
4. Skeleton – Information Design, UI Design, Navigation Design
5. Surface – Sensory Design (e.g., Visual Design, Audial Design)

UI Design practically comes after having objectives and requirements. It constitutes the design of the interface based on Information Architecture and Interaction Design.

The Elements of UX shows the abstraction of what constitutes UX Design. It involves the whole process of research and testing at different planes and at different stages of the process.

Now, must a UI designer dive right into UI design without referring to any previous work done such as objectives and requirements, information architecture and interaction designs?

Originally published in Quora