When choosing between Next.js and React, it’s crucial to understand their distinctions. React is a flexible library for building user interfaces, focusing on component-based architecture and client-side rendering. Next.js, built on top of React, adds server-side rendering, static site generation, and built-in routing, enhancing performance and SEO. Use React for applications needing dynamic UIs and client-side interactivity, while Next.js excels in projects requiring optimized performance, SEO, and server-side rendering. For instance, Next.js is ideal for eCommerce sites needing fast load times and better search engine visibility, while React suits interactive dashboards or single-page apps.