Cittas can be classified by way of jāti (jāti literally means 'birth' or 'nature').
There are four jatis: akusala, kusala, vipāka, kiriyā.
Both kusala vipāka (the result of a wholesome deed) and akusala vipāka (the
result of an unwholesome deed) are one jāti, the jāti of vipāka.
It is important to know which jāti a citta is. We cannot develop
wholesomeness in our life if we take akusala for kusala or if we take akusala
for vipāka. For instance, when we hear unpleasant words, the moment of
experiencing the sound (hearing-consciousness) is akusala vipāka, the
result of an unwholesome deed we performed ourselves. But the aversion
which may arise very shortly afterwards is not vipāka, but it arises with
akusala citta. We can learn to distinguish these moments from each other
by realizing their different characteristics.