Visual Design:

Crafting the overall look and feel (color palettes, typography, iconography).

Interactivity & Animation: Designing how elements respond to user input (e.g., a button changing color when hovered).

Style Guides & Design Systems: Creating a consistent set of visual rules and reusable components for the product.

High-Fidelity Mockups and Prototypes: Pixel-perfect visual representations of the final product.

A UI Designer is like an interior designer, who takes the architect's plans and makes the space beautiful, cohesive, and pleasant to be in.