Χαρακτηριστικές λεπτομέρειες των ειδών Lycae
These two species are very similar. Shaded veins may be a criterion for separation. The distribution maps in Greece and photos of Pieris napi are listed (with marked characteristic points on the wings that exist in some individuals only).
See also the website here where a seperation criterion is proposed between the species Pieris napi Pieris balcana and is to be investigated.