Cholesterol present in LDL
On accumulation in the cell inhibits replenishment of LDL receptors

If LDL cholesterol is increased inside the cell, it down regulates LDL receptors so that further uptake is inhibited.
HDL cholesterol is the cholesterol that is removed from peripheral tissues; LDL cholesterol represents the cholesterol which is to be delivered to peripheral tissues.
LDL binds to LDL receptors and whole LDL particle is endocytosed by receptor mediated endocytosis via clathrin-coated pits (not by diffusion:- diffusion and endocytosis are different processes).
Intracellular cholesterol activates intracellular enzyme acyl-CoA cholesterol acyl transferase (ACAT).
Represents primarily cholesterol that is being removed from peripheral cells
Binds to a receptor and diffuses across the cell membrane
On accumulation in the cell inhibits replenishment of LDL receptors
When enters a cell, suppresses activity of acyl-CoA; cholesterol acytransferase ACAT