A tumour is any abnormal growth of cells in the human body. If the cells have not only multiplied more than they should have done, but have also changed in appearance so that they have become abnormal, then these cells are considered to be cancerous or malignant (the meaning is the same in this context). However, the word malignant also has a general meaning in English - it means 'harmful.' Because of this there are many other diseases in English that do not involve cancer but where the name of the disease begins with the word "Malignant." A neoplasm is another word for tumour. A Carcinoma is a particular type of cancerous tumour which can only occur in certain types of cell in the human body. They form in what is known as epithelial tissue and in the tissue of the internal organs. Cancers which form in other types of tissue are given other names in English. For example, a tumour of the connective tissues of the body is known as a Sarcoma.

tumor and neoplasm are synonyms ... their meaning is an abnormal increase of cells' number or size .. according to their effect on human's body they divided into to types >> malignant (harmful and invasive) and benign (unharmful and non-invasive) ... the malignant tumors always called cancers but not the benign ones

They are all the same.

Are you in medical school?