Well, a cube actually is a special type of rectangular prism! It just happens to be one that has all square faces.... Just like a square is a special type of rectangle that has equal sides. A rectangular prism has rectangular faces that may not all be equal. However, it will have the same number of faces, vertices, and edges as a cube (rectangular prism with equal square faces).
The rectangular prism contains equal number of faces , edges and vertices. Because the rectangular prism like cube contains special types of rectangles those are all have same number of faces, edges and vertices. But those are not equal length and sizes.