What is the difference between repentance (توبة) and seeking forgiveness (استغفار)?

Repentance includes regretting the past, abandoning the sin in the present, and resolving not to return to it in the future, whereas seeking forgiveness (Istighfar) is asking for forgiveness, covering the sin, and protection from its punishment. Repentance entails seeking forgiveness, but seeking forgiveness does not necessarily mean repentance.