1, the components are different: a cylinder consists of a circle and an axis parallel to the circle, with a rectangular side and two bottom faces of the same circle. The side of the cylinder is rectangular, and the two bottom surfaces are the same circle.

2. Different sizes: the cylinder is a two-dimensional geometric figure with a rectangular side and no thickness. The cylinder is a solid geometry, and the side is a rectangle with a certain thickness.

3. Different usage scenarios: the cylinder is a three-dimensional geometric body, which is common in the real world and is often used to describe the shape of objects, cylindrical containers, cylinders and so on. As a kind of two-dimensional geometry, cylinder is more used in theoretical research of mathematics and geometry.