Question

what is the difference between antibody and antitoxin?

Answer 1

Antibodies a small protein chains white blood cells release in the bloodstream to attach to viruses keeping then from attaching to the membranes of cells. 
An anti toxin is a chemical substance that aims to defend from another harmful chemical substance (the toxin), and is generally man-made.

Answer 2

Antibodies are proteins produced by the immune system in response to any pathogen. Thay can either destroy, kill or inactivate pathogens.
Antitoxins are a special group or type of antibodies which render a toxic substance harmless. It can neutralize a specific toxin.