The cell membrane, also known as the plasma membrane, controls the movement of substances in and out of a cell. "cytoplasmic membrane" is the same as "cell membrane"; they are both terms used to describe the outer boundary of a cell that separates the cell's interior from the external environment, and it's also sometimes called the "plasma membrane". 

• The cell membrane is a semipermeable lipid bilayer that surrounds the cell. 
• It separates the inside of the cell from the outside environment. 
• The cell membrane is selectively permeable, meaning it allows some substances to pass through but not others. 
• The cell membrane regulates the transport of materials entering and exiting the cell.