Both, bricks in a building and cells in the living organisms, are basic structural units . The
buildings, though built of similar bricks, have different designs, shapes and sizes. Similarly, in the living world, organisms differ from one another but all are made up of cells. Cells in the living organisms are complex living structures unlike non-living bricks. The egg of a hen epresents a single cell and is big enough to be seen by the unaided eye.
Cell - Structure and Functions - Notes
6. Comparison of Plant and Animal Cells