What is difference between overactive bladder and interstitial cystisis? I have urtheral discomfort and urgency/frequency especial at night.

Presence of pain. Interstitial cystitis is typically associated with a painful bladder , whereas overactive bladder or urgency tend to be associated with frequency of needing to void. These are often associated or confused with urinary tract infections. Diagnosis treatment can be complex... See your doctor.