The devise gem and the devise_token_auth gem are both authentication solutions for Ruby on Rails applications, but they serve different purposes. Here’s a brief explanation of the difference between devise and devise_token_auth:

1. Devise:
   • Devise is a popular authentication solution for Ruby on Rails applications.
   • It provides a comprehensive set of features for user authentication, including registration, login, password reset, session management, and more.
   • Devise uses cookies and session-based authentication by default, providing a traditional server-side authentication mechanism.
   • It offers a variety of configuration options, customizable views, and convenient helper methods to handle authentication-related tasks.
   • Devise supports multiple authentication strategies, such as database authentication, token authentication, and third-party authentication using OAuth providers.
2. Devise Token Auth:
   • Devise Token Auth (devise_token_auth) is an extension of the Devise gem that adds token-based authentication capabilities to your application.
   • It is designed specifically for creating APIs or applications that require token-based authentication (e.g., mobile apps, single-page applications).
   • Devise Token Auth introduces a token-based authentication approach using JSON Web Tokens (JWT) or simple tokens.
   • Instead of relying on cookies and session-based authentication, Devise Token Auth allows clients to authenticate by sending tokens in the request headers.
   • It provides API endpoints for user registration, login, token refresh, token validation, and more, which can be used in conjunction with frontend frameworks or external clients.
   • Devise Token Auth also includes features like token expiration, token revocation, and token management.

In summary, devise is a full-featured authentication gem that provides traditional cookie-based authentication for Rails applications. On the other hand, devise_token_auth is an extension of devise that focuses on token-based authentication, primarily used for building APIs or applications that require stateless authentication with tokens sent in request headers.