The major difference between brain metastases and brain tumors is the tissue of origin and how the conditions develop. A primary brain tumor is a condition such as a glioma or vestibular schwannoma, which is made up of cells that naturally occur within the brain. In contrast, brain metastases are made up of cancer cells from another site in the body, like the lung or breast. These cells spread (metastasize) from elsewhere in the body and have grown into tumors in the brain.
Please read our full post to learn more about the differences between Brain Metastases and Brain Tumors.