TAXONOMY

The taxonometric way of classifying organisms is based on similarities between different organisms. A biologist named Carolus Linnaeus started this naming system. He also chose to use Latin words. 
Taxonomy used to be called Systematics. That system grouped animals and plants by characteristics and relationships. Scientists looked at the characteristics (traits) that each organism had in common.

RULES OF TAXONOMY

Every known living organism on Earth is classified and named by a set of rules. Those rules are used by all scientists around the planet. The names are called scientific names, not common names. Common names are the ones you might use when talking with your friends. You call your pet a dog or a cat (the common name). Scientists call those animals by a set of several names like Canis familiarus. That's a dog. 

http://www.biology4kids.com/files/studies_taxonomy.html

CLASSIFICATION

Scientists believe that there are over 10 million different kinds of lifeforms, or species, on Earth. Imagine trying to study and understand the lives, patterns, behaviors and evolution of so many different kinds of organisms. In order to make their job easier, scientists classify living things into groups based on how they are the same and how they are different.

Scientists who classify living things are called taxonomists. It is their job to look at every kind of living thing and determine how they are similar and how they are different to other living things.

http://www.kidsbiology.com/biology_basics/classification/kingdom3.php