You can't tell by leaf shape this early with passiflora. The petiole glands may be a more accurate identifier, but most likely you'll have to wait until the plant's 12" tall or so before being sure.

Jamie is right!!!
I have some of both started... It looks like a P.Quadrangularis when I compare it to mine.. I will post the pic if you want... They are all about the same size...
Chena

Definitely P.quadrangularis from the large square shaped leaf, p. ligularis has heart shaped leaf.