Answer:
Phosphate group.
Step-by-step explanation:
One of the form of lipids is triglycerides.
Triglycerides are the lipids which have one glycerol molecule bonded with three fatty acid chains, so it is a triester of glycerol hence known as triglycerides.
In case of phospholipids also there is a glycerol molecule to which two fatty acids are bonded and in place of third fatty acid it has a phosphate group which makes it different from other lipids or triglycerides.