Have you ever tried scaling a photo, and noticed how pixelated it becomes? This is the difference between a “rasterized” image and a vector.
Vectors, unlike rasterized images are made of fixed pixels and are digitally designed. They can be scaled at any size without loss of quality of degradation. Which means your logo, your t-shirt design or your slogan will always look its best.
Most modern printing formats encourage vector images. The result is the highest printing quality.