@simrin-- That's an excellent question.
An anti-toxin tetanus shot contains tetanus antibodies. Antibodies are what our body produces to fight an infection. Anti-toxins are the preferred treatment when a person or animal already has the tetanus bacteria. It will help the body fight the infection and the toxins released by it.
A toxoid shot contains the actual tetanus bacteria, but it's weakened so it can't cause an infection. It works by triggering a reaction by the immune system. This is the preferred treatment for those at risk of a tetanus infection. It provides long-term protection.