The shape of a lamp determines how wide or narrow the light beam is.
A directional lamp, such as a spotlight or reflector lamp, has a beam narrower than 90°.
Decorative use: to emphasise an object by lighting it in a focused way.
Practical use: to precisely illuminate a work surface, such as a countertop.
Are you looking for more widely dispersed light, for example for general lighting of a room? Then a lamp with a round beam is more suitable, as the light spreads more evenly.
In short: the shape of the lamp and the beam angle determine how and where the light falls, and are essential when choosing the right lighting for your space or application.