If you’re exporting a PNG or a JPEG, your vector image becomes raster at that point. Think of the end products of your work: if you are designing something for print, your vector image will be translated by the printer software into a grid that the printer itself represents in tiny ink dots. Vector software is really just another way of producing raster images. It’s not entirely fair because virtually everything you produce in software ends up as raster of some sort. This isn’t really a fair distinction, but it is the impression many people have when comparing the two image types. Here’s the same curve, the vector version on the left and the raster on the right: If you make the grid image much larger, you’ll end up with larger grid squares. The point of this distinction between images defined by vectors and images defined by a grid is that you can make the vector image much larger and it’ll look just as detailed. There are roughly 50 pixels in each dimension, enough to describe basic shapes, but not much use for anything more detailed. In this case, the colour of each pixel varies from black to grey to white to give the illusion of a curve.

This is the same curve as above, but the grid of pixels is much larger to make the construction more obvious: Within the grid, each square (or pixel) is assigned a colour value, and an image emerges from the arrangement of squares.

“Raster” means something is defined by a grid.

How to change image size in illustrator