A ray of light or light rays are the direction along which the light energy travels. In practice a ray has a finite width and is represented in diagrams as straight lines.
A beam of light is a collection of rays. A search light emits a parallel beam of light (Fig: a). Light from a lamp travels in all directions which is a divergent beam. (Fig: b). A convex lens produces a convergent beam of light, when a parallel beam falls on it (Fig: c).