In other words, with a model of a car, you could change the size of the tires without affecting the rest of the car. You could stretch the body of the car without deforming the tires. These early computer graphics were Vector graphics, composed of thin lines whereas modern day graphics are Raster based using pixels. The difference between vector graphics and raster graphics can be illustrated with a shipwrecked sailor. The rock SOS sign is similar to raster graphics.
Every pixel has to be individually accounted for.
The rope SOS sign is equivalent to vector graphics. The computer simply sets the starting point and ending point for the line and perhaps bend it a little between the two end points. The disadvantages to vector files are that they cannot represent continuous tone images and they are limited in the number of colors available. Raster formats on the other hand work well for continuous tone images and can reproduce as many colors as needed. Also in 1961 another student at MIT, Steve Russell, created the first video game, Spacewar.