The characteristic common to both plant and animal cells is the presence of a cell membrane.

Here's why:

* Cell membrane: This is the outer boundary of all cells, controlling what enters and exits the cell. It's essential for maintaining the cell's internal environment.

While both plant and animal cells have a cell membrane, they also have some differences:

* Plant cells: Have a cell wall outside the cell membrane, providing structural support. They also have chloroplasts for photosynthesis and large vacuoles for storage.

* Animal cells: Lack cell walls and chloroplasts. They often have smaller vacuoles or multiple small vacuoles.

Let me know if you'd like to know more about plant or animal cell characteristics!