Difference between Ureotelism and Uricotelism.

Hint: Ammonia is the most toxic form and requires large amounts of water for it is elimination. Urea and uric acid are less toxic forms of nitrogen wastes and they require less water for their elimination.

Complete answer:
Ammonotelism-Animals which excrete ammonia are called Ammonotelic and excretion of ammonia is termed as the Ammonitelic.
Examples of Ammonotelic animals are bony fishes, aquatic amphibians and aquatic insects.
Ureotelism- Terrestrial animals should produce less toxic nitrogenous waste such as urea and uric acid to save water.
The process of excretion of urea is termed as ureotelism.
In these animals ammonia produced by metabolism is converted into urea by metabolism in the liver if these animals by ornithine cycle.
Examples of ureotelic animals-Mammals , many terrestrial amphibians and marine fishes etc.
Uricotelism-These animals excrete nitrogenous waste in the form of paste or pellets with minimum loss of water are called uricotelic animals . The process of excretion of uric acid is termed as uricotelism.

Example of uricotelic animals-Reptiles, birds, insects and land snails.

Note: Urea synthesis is a biochemical aspect of excretion. It is also known as kreb-Henseleit cycle; it can occur in livers .
Excretion is the removal of metabolic wastes from the body. Removal of undigested waste is called defecation or egestion.
Carbon dioxide and water are metabolic wastes of carbohydrates and fat metabolism, Therefore their removal is called excretion.