@Size vs @Length vs @Column

@Size and @Length are similar which are used to validate the size of a field. The first is a Java-standard annotation and the second is specific to Hibernate. Whereas @Column, is a JPA annotation that we use to control DDL statements.

Example for @Size
This annotation makes the bean independent of JPA and its vendors such as Hibernate

public class Customer {
    ...
    @Size(min = 5, max = 15)
    private String fullName;
    ...
}

Example for @Length
It is Hibernate-specific version of @Size

@Entity
public class Customer {
    …
    @Length(min = 5, max = 15)
    private String fullName;
    …
}

Example for @Column
It is used to indicate specific characteristics of the physical database column.

@Entity
public class Customer {
    …
    @Column(length = 15)
    private String fullName;
    …
}