No! These are completely separate and require different skills and techniques. I’m skeptical if any one individual who claims to be an expert in both. They do exist, but are rare.
UX (user experience) is all about researching what users want from something (in our context, a website). This involves getting into the mindset of typical users (or target users) and ensuring the entire digital journey is optimised for them.
UI (user interface) is all about designing the front end (in our context, a website) that looks nice, clean, intuitive, functional, reflecting well on the organisation.
Good web teams (either project or business as usual teams) will have both UX and UI specialists working well together. The UX specialist should be deeply engaged with user research, defining user personas, user needs (usually expressed in the format “as a.. I want to... so that I...”), looking at current user journeys (mapping these) and analytics (such as Google Analytics). The UI will be looking at corporate branding, themes, wireframes and architecture.
At early stages both can be done in parallel but at some point they need to come together so that the designs become optimised based on both the users and the organisation.
At Ellipse Atlantic, we provide training on both UX and UI and in particular how these work well together in a team to get the right result.