A localized brain tumour is found in just one place and is usually easier to remove provided it's in a part of the brain the surgeon can reach easily. An invasive tumour spreads and is more difficult to remove completely. The grade of a tumour tells you how aggressive it is. A low grade means a less aggressive tumour and a better chance for a cure. A higher grade means a more aggressive tumour and a lower chance for a cure.
Attribution: Straight Talk Foundation