About This Answer
Asked about the relationship between citta and viññāṇa, sense consciousness, Ajahn Dtun says the two words are commonly used together, but they are actually distinctly separate. Viññāṇa is the knowing of sensory contact: whenever sense contact takes place, viññāṇa is what knows it. In truth, that is not the citta.
The difference becomes clear in practice. Once one gradually lets go of the coarser defilements, such as greed and anger, satisfaction and dissatisfaction, and starts working on the subtler ones, one is dealing with the workings of the mind itself, and that is when the two begin to separate out.