Difference between Subquery and Correlated Subquery

select UserID,
                                          FirstName,
                                          LastName,
                                          DOB,
                                          GFName,
                                          GLName,                                      
                                          LoginName,
                                          LoginEffectiveDate,
                                          LoginExpiryDate,
                                          Password,
                                          Email,
                                          ReportingTo,
                                          Mobile,
                                          CommunicationPreference,
                                          IsActive
                                          from (
                                          select row_number() over (order by FirstName) as Row,
                                          UserID,
                                          FirstName,
                                          LastName,
                                          DOB,
                                          GFName,
                                          GLName,
                                          LoginName,
                                          LoginEffectiveDate,
                                          LoginExpiryDate,
                                          Password,
                                          Email,
                                          ReportingTo,                                    
                                          Mobile,
                                          CommunicationPreference,
                                          IsActive
                                          from DivakarUserRegistration