A raster image is an assembly of individual pixels of color arranged to form an image, also known as bitmaps. From a visual design aspect, raster images are simple to make smaller, but making them larger is tricky. Increasing the size of a raster image will decrease the resolution, making your picture blurry or fuzzy.
A vector image is defined on a plane by connecting curves and lines, and it uses mathematical equations to form shapes. It allows you to create more refined and detailed artwork. No matter how far you zoom in or out on the image, it will stay true to the design, without pixelization.