What is difference bettwen symptoms of benign and malignant ovarian tumor?

Not much: There usually aren't many symptoms to tumors on the ovary whether benign or malignant. Malignancy is associated with weight loss, night sweats and fatigue.

Should see Doctor: Until late in the course of a malignant ovarian tumor there are very few specific symptoms. With both malignant and benign tumors some describe a feeling of pelvic or lower abdomen fullness or in some cases pain with intercourse or during their period. If you suspect a problem I would talk to my primary care provider.

Ascites of spread: When benign as well as malignant ovarian tumors incvluding cysts develop, the lesions are localized and essentially asymptomatic. The malignant lesion will of course spread to both uterus, the other ovary as well as omentum due to presence of TGF-b. Here vascular permeability factor is secreted with resulting ascites.