How are malignant tumors different from benign tumors?

Malignant tumors are much more harmful. It is cancerous and can spread to the rest of the body. Benign are not cancer and do not spread. They are not a big deal unless they are pressing on something like vital blood vessels or nerves. I remember the difference by looking at the prefix on these words. Mal means bad (like mal-practice) and ben means good (like beneficial)