Is there a difference in symptoms associated with ovarian cysts and ovarian cancer?

No: Ovarian ca may cause pain and appear as a cystic mass on ultrasound, just like a benign ovarian cyst. Ovarian cancer may occur in pre- and post-menopausal women. It is often associated with gastro-intestinal symptoms. Most cysts in pre-menopausal women are benign, but, you must see your gyn regularly to follow it.

Difficult : Difficult to discern just by symptoms, needs an evaluation by a physician to work up in detail.