How is dialysis tubing different from a cell membrane?

Materials can move into the plasma membrane through both active and passive transport. Molecules that are too big to move into the plasma membrane are usually transported through passive transport by carrier proteins. Thus, both small and big particles can move into the cell via the plasma membrane.

In contrast, the dialysis tubing is designed in such a way that only fine particles [water] can pass through the tubing. Movement into the tubing is based on pore size.