Cladograms
A cladogram is a branching diagram that shows derived and shared characteristics between animals and how two animals may look very different but actuallu share some similar characteristics. For example, on the left we see a few very different animals. You may think "How can a turtle, a horse, and a houde cat be alike?" but the truth is they belong to the same domain, Eukarya, kingdom, Animalia, and phylum, Chordata. From the turtle to the house cat, all the animals on the chart share one characteristic; their backbones. From the horse to the house cat the all share another characteristic that the turtle does not; fur. The wolf, leopard, and house cat all have carnivorous teeth. The horse and turtle do not. Unlike the wolf, horse and turtle, the leopard and house cat have retractable claws. And lastly the house cat is the only one out of the five that has the ability to purr. This is how a cladogram works.
Dichotomous Keys
A dichotomous key is a diagram that asks you questions about the traits of an organism to find out what it is. On the right there is a very simple example of a dichotomous key. If you are looking at an animal and you are using this key to decide what it is, you ask yourself a few questions. First you ask yourself, "Does my animal have feathers?" Lets just say that your animal does indeed have feathers, so you move on the the next question, "Does it swim?". So, you go down to the pond and casually throw your animal into the water and it begins to paddle its legs. It swims! According to the key, you have a duck. Dichotomous keys are helpful when you are unfamiliar with the organism you are observing. They are a quick and easy way to find out exactly what it is you are looking at.