Better name for a square prism
Because all the angles are right angles, it's a cuboid.
Because it has the same cross-section along its length, it's a prism.
Because all the faces are rectangles of one sort or another, it's a rectangular prism.
Because two opposite faces are squares, it's a square prism.
Because all faces are not the same size, it's not a cube.
Reference: Maths is fun
A prism where two opposite sides are triangles is called a triangular prism. What a prism is called is determined by the faces which are not rectangles.