Prisms and pyramids are two different types of three-dimensional geometric solids. The most obvious similarity is that both begin with the letter P.
In both prisms and pyramids, all the faces including the base are polygons. This is where the similarities between the two geometric shapes end, although in practice prisms and pyramids are often mistaken for each other.
A pyramid has a single base and all faces are triangles which converge at a single vertex. In contrast, a prism has two congruent bases which are parallel and all the faces are parallelograms. The faces of a prism may be any type of polygon, and the type of prism takes its name from the shape of the faces; triangular prism, for example.