Spring MVC vs Spring REST — View-Based vs API-Based

Direct Answer

'Spring REST' is not a separate framework from Spring MVC. Spring MVC can render server-side views or write response bodies for HTTP APIs. @Controller and @RestController are common choices, but either style can return ResponseEntity and a @Controller method can add @ResponseBody. The real difference is return-value handling and the endpoint contract, not an absolute controller annotation split.

Code Example

// Spring MVC - returns view name, renders HTML
@Controller
public class UserMvcController {
    @GetMapping("/users/{id}")
    public String getUser(@PathVariable Long id, Model model) {
        var user = userService.findById(id);
        model.addAttribute("user", user);
        return "user-profile"; // Thymeleaf renders user-profile.html
    }
}

// Spring REST - returns object, serialized to JSON
@RestController // Same as @Controller + @ResponseBody on all methods
@RequestMapping("/api/users")
public class UserRestController {
    @GetMapping("/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.findById(id); // Returns JSON: {"id":1,"name":"Alice"}
    }
}

// You can mix both in one controller with @ResponseBody
@Controller
public class MixedController {
    @GetMapping("/page")
    public String htmlPage() { return "view"; } // HTML
    
    @GetMapping("/data")
    @ResponseBody // Makes this method return JSON instead of view
    public User jsonData() { return new User(1L, "Bob"); }
}

Common Mistakes & Pitfalls

• Thinking they're separate frameworks: Freshers believe Spring REST is a different module or framework from Spring MVC. They're the same — @RestController is just syntactic sugar for @Controller with @ResponseBody on every method. Both use DispatcherServlet.
• Returning view names from @RestController: Writing return "user-list"; in a RestController method and expecting JSON. RestController treats String returns as literal response body, not view names. You'll get the string "user-list" as plain text, not JSON.
• Mixing concerns: Adding Model parameters to RestController methods or returning ResponseEntity from @Controller methods without @ResponseBody. If you need JSON, use @RestController. If you need views, use @Controller. Don't mix unless you explicitly use @ResponseBody on specific methods.