Nodules are more different from tumours in that nodules usually occur in the epidermis, sub-dermis or subcutaneous tissue and can be palpated by palpation, whereas tumours tend to occur in internal organs and are difficult to palpate by palpation and are usually identified by imaging that reveals shadows of varying density.
(b) A nodule is a palpable, elevated, substantial lesion, whereas a tumour is a new organism formed by the proliferation of local tissue cells in the body in response to various tumourigenic factors.
A nodule may also be an inflammatory change that does not necessarily require surgical treatment, whereas most tumours, whether benign or malignant, need to be surgically removed as soon as possible.