What is the difference between repentance (توبة) and seeking forgiveness (استغفار), and is seeking forgiveness beneficial without repentance?

Both repentance (توبة) and seeking forgiveness (استغفار) are independent causes for forgiveness. Repentance mends the past, present, and future, whereas seeking forgiveness is intended to mend the past. Seeking forgiveness is a request for forgiveness through supplication, while repentance is remorse for a sin coupled with a firm resolve not to repeat it. Seeking forgiveness pertains to a past sin, and repentance pertains to what is to come, and seeking forgiveness is not beneficial when there is persistence [in sin]. Absolute seeking of forgiveness is like repentance, and it prevents punishment. As for one who persists in sin and seeks forgiveness, it is not an absolute seeking of forgiveness.