Similarities:
A cylinder has 2 flat ends and a curved surface while a prism has two polygons for the two ends and the rest are plain rectangular faces. A cylinder has no vertices while a prism has several vertices. A cylinder has two curved edges while a prism has no curved edge. A cylinder has no diagonals while a prism has many.
Differences:
is that prism is (geometry) a polyhedron with parallel ends of the same size and shape, the other faces being parallelogram-shaped sides while cylinder is (geometry) a solid figure bounded by a cylinder and two parallel planes intersecting the cylinder.