The two cellular structures found in animal cells but not in plant cells are the centrosome and the lysosome. The centrosome is the microtubule-organizing center of the cell, giving rise to the mitotic spindle. The lysosome is the cellular disposal system, breaking down unwanted materials from the cytoplasm.
Animal and plant cells are both eukaryotic, which means they contain a nucleus and other membrane-bound organelles. However, there are several differences between plant and animal cellular structures: plant cells have rigid cell walls and chloroplasts; animal cells have centrosomes and lysosomes.
The unique cellular structures present in animal cells do not make animals distinctly different from plants. Whether it is necessary for a cell to have a centrosome is still unknown, as cells with their centrosome removed can still undergo mitosis and meiosis. The waste-disposal function of the lysosome in animal cells is carried out by the vacuole in plant cells.
Conversely, the unique structures present in plant cells make plants distinctly different from animals. Cell walls make plant cells rigid and give plants the capacity to grow much taller than animals in a terrestrial environment. Chloroplasts allow plants to capture energy from the sun and transform that energy into carbohydrates through photosynthesis. Animals cannot capture energy from the sun and therefore must consume plants for their source of carbohydrates.