The difference between bladder tumors and bladder cancer generally lies in whether the growth inside the bladder is benign or malignant. Normally, nothing should grow inside the bladder. However, if a growth does appear, it can be referred to as a bladder tumor if it is benign, or bladder cancer if it is malignant. Bladder tumors are typically round with clear boundaries, which can be observed through ultrasound or cystoscopy. On the other hand, if the growth in the bladder resembles seaweed or cauliflower, with unclear boundaries, erosion, bleeding, or other symptoms, it can be referred to as bladder cancer. Generally, the primary treatment for such cases is surgical removal.