In this context, let me just say that PSD2 as well as banking legislation govern the respective activities and that an institutional licence is required to conduct them, which implies that the entities will be supervised in line with the risks involved. Payment institutions are only allowed to provide a limited set of services, i.e. payment services.
They are not allowed to take deposits and are only allowed to hold funds for the provision of payments. Credit institutions, by contrast, have a much wider scope of activities than payment institutions; they can engage in the whole spectrum of banking activities, including the holding of deposits and the granting of loans.