The simplest way to think about it is: Flexbox is for laying out items in a single dimension (a row OR a column). Grid is for laying out items in two dimensions (rows AND columns).

When to Use Flexbox

Flexbox excels at aligning content within a component. Think of navigation bars, form controls, or a row of cards. It's perfect for distributing space along a single axis.

When to Use Grid

Grid is the ideal choice for the overall page layout. It allows you to define columns and rows, creating a scaffold for your main content areas, sidebars, headers, and footers. The two can be used together for powerful, flexible designs.