The different things between organisms number 1.its like the plover and the crocodile the crocodile lies with its mouth open and a plover bird comes over to pick the meat out of the crocodiles teeth but the crocodile does not eat the bird but likes the dental work that the bird is doing so the bird eat the meat that's is in the crocodile teeth so it a fair share bird clean the meat out of the crocodile teeth and the bird eat the meat from the crocodiles teeth.

And number 2 is only one species benefits while the other is neither helped or harmed example the remora fish are very bony and have a dorsal fin that acts like a suction cup. The remora fish uses the fin to attach themselves to whales,shark or stingrays and eat the scraps that they leave behind the remora fish gets the meal while the host gets nothing selfish but neither get hurt.

The last one number 3 the parasite is one organism gains while the other one suffers the deer tick is a parasite it attaches to a warm blood animal and feeds off of its warm blood and it need blood at every stage of its life and it carry a disease that hurts the joint damage and heart and kidney problems with that the loss of blood and loss of nutrients and get sick.