Antibodies cling onto antigens to either sterilize or kill the target cell. Other than that, they are very different in function. Antigens are locks or security gates in a cell, Antibodies are weapons or keys to attack and destroy a cell. They are ultimately two opposite things.
Here is a video explaining the difference:
Antibody versus Antigen comparison chart
What it is
A chemical that attaches to the antigen in order to sterilize or kill the cell.
A 'hook' in the cell's surface, partially responsible for what goes in and out of the body.
Medium; needed for the destruction of pathogens in the body.
High; exists in almost every cell in the entire world.
High; without it a lot of us would probably be dead by a virus attack.
Very high; needed for controlling what goes in and out of the cell. Very important for it's inner function.
Very High; Complex chemical that bonds to a very specific Antigen.
Medium; exists due to random mutations in the cell's gene.