Here are some key changes you’ll encounter when moving from Create React App (CRA) to Next.js:

Build Tools:

• CRA: Uses Webpack for bundling and development server.
• Next.js: Uses Webpack internally but has its own custom build process and development server optimized for performance.

File Structure:

• CRA: Has a more basic folder structure with src for components, public for static assets, and package.json for dependencies.
• Next.js: Introduces the pages directory for defining application routes and uses public for static assets. The project can contain additional directories like components and api for organizing code.

Rendering:

• CRA: Primarily uses client-side rendering (CSR) where the UI is rendered in the browser.
• Next.js: Offers multiple rendering options like server-side rendering (SSR), static site generation (SSG), and incremental static regeneration (ISR). This allows for faster initial page loads and improved SEO.

Routing:

• CRA: Uses React Router for navigating between different application views.
• Next.js: Has built-in routing through the pages directory. Each file in pages corresponds to a route, making routing more intuitive and integrated with file structure.

DataFetching:

• CRA: Requires manual setup using libraries like fetch or Axios for data fetching.
• Next.js: Provides built-in functions like getStaticProps, getServerSideProps, and getInitialProps for fetching data at build time, server-side, or client-side respectively, simplifying data management.

API Routes:

• CRA: Requires external server setup for handling API requests.
• Next.js: Allows defining API routes directly within the project using files in the api directory. This enables creating server-side functionalities without additional setup.

Additional Features:

• Next.js: Offers built-in features like image optimization, prefetching, code splitting, and automatic code updates, which can improve performance and developer experience.

Overall:

• CRA: More basic, suitable for small to medium-sized projects with simple routing and data needs.
• Next.js: More complex but offers significant performance and SEO benefits, ideal for larger projects or projects requiring SSR or SSG.

Before choosing, consider your project’s requirements and complexity to determine which framework best suits your needs.