tumor in the bladder?

It is usually called a growth because the aetiology (nature of the cells are not known). A specialist will not provide an accurate diagnosis until s/he has the pathological (nature of disease cells) facts and can provide a clear provisional (probably that) diagnosis and suggest treatment. The type of cells that constitute the growth are very significant and may be the difference of it beginning a localised growth or metastatic (cancer spreading through the body). Slow growing space occupying tumours (growths) may damage the surrounding tissues by blocking off blood supply or crushing the healthy cells (for example). A Basal Cell Carcinoma (BCC) grows usually on the skin and puts pressure on normal cells around it. I've tried to keep it simple, by putting bracketed lay meanings after medical terms. I'll try again if you need something else.

It's personal preference. A tumor IS a growth just as a cancer IS a growth. It's like looking at a picture of chef Ramsay and you saying, "He's so hot" and I say "He is so cute". We're saying the same thing, just two different ways.