Here's why:
* Phylum: Snails belong to the phylum Mollusca, while monkeys belong to the phylum Chordata. This is a very fundamental difference in their classification.
* Class: Snails are further classified into the class Gastropoda, while monkeys are classified into the class Mammalia.
* Evolutionary History: Snails and monkeys have vastly different evolutionary histories. Monkeys are mammals with a complex evolutionary lineage that includes primates. Snails are invertebrates with a much older and different evolutionary path.
In simple terms, snails are invertebrates (animals without backbones) while monkeys are mammals (animals with backbones, fur, and milk-producing glands). They are very different creatures with distinct evolutionary paths.