Aristotle classified animals on the basis of habitat.  For example, corals, whales, octopuses, star fish and sharks lived in sea were placed in one group even when they are very different from each other  Except habitat, they do not share other similarities. Thus it was not an efficient way to classify animals and hence was discarded. 

Blue whale is 30 metre long and largest animal.

Redwood trees of California are 100 metre tall and are longest tree.

Characteristic is a particular form or a particular function. For example, generally human being has five finger on each hand. Thus, presence of five finger on each hand is a characteristic. Similarly, animals can run but tree like banyan tree cannot run, is also a characteristic.

Aristotle classified animals according to whether they lived on land, in water or in the air.

Arranging the organisms into different groups on the basis of similarities and differences  is known as classification.