How does a benign tumor differ from a malignant tumor? does the same therapy shrink both of them?

No: Most benign tumors are not capable of spreading an invading distant organs. That being said, there are rare examples of benign tumors that get so big that they can cause major symptoms and medical problems. Thankfully, these are pretty unusual. Chemotherapy is not usually effective for benign tumors; surgical removal is a better option.

A benign tumor: Never metastasizes, but can grow in impair an organ function or encroach on neighboring ones. Under the microscope, there are atypical to bizarre cells in malignant tumors, whereas the benign tend to be bland.