DTO (Data Transfer Object)

Data Transfer Object is a pattern whose aim is to transport data between layers and tiers of a program. A DTO should contain NO business logic

public class UserDTO {
    String firstName;
    String lastName;
    List<String> groups;

    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public List<String> getGroups() {
        return groups;
    }
    public void setGroups(List<String> groups) {
        this.groups = groups;
    }
}

Java Beans

Java Beans are classes that follows certain conventions or event better they are Sun/Oracle standards/specifications as explained here:

https://www.oracle.com/technetwork/java/javase/documentation/spec-136004.html

Essentially, Java Beans adhere to the following:

• all properties are private (and they are accessed through getters and setters);
• they have zero-arg constructors (aka default constructors)
• they implement the Serializable Interface

The main reason why we use Java Beans is to encapsulate

public classBeanClassExample() implements java.io.Serializable {

  private int id;

  //no-arg constructor
  public BeanClassExample() {
  }

  public int getId() {
    return id;
  }

  public void setId(int id) {
    this.id = id;
  }
}

So, yeah what is the real difference? If any?

In a nutshell, Java Beans follow strict conditions (as discussed above) and contain no behaviour (as opposed to states), except made for storage, retrieval, serialization and deserialization. It is indeed a specification, while DTO (Data Transfer Object) is a Pattern on its own. It is more than acceptable to use a Java Bean to implement a DTO pattern.