Difference between Pin (Punya) and Kusal(Kushala)?
Pin(Punya) and Kusal are both same. Pin means that which purifies the mind. Kusala means that which is born of wisdom or that which counters defilements. The good deeds that lead to birth in heavenly realms are called Wattagamini-Kusala and the good deeds that lead to Nibbana are called Viwattagamini-Kusala. Here's an explanation by ven. Nauyane Ariyadhamma Thera.