Physiological variation is when members of the same species react to their environment differently. Here are some examples of physiological variation in humans and animals. E.g People have different abilities to taste phenylthiocarbamide (PTC), roll their tongues, and have different blood types.

Morphological variation is the difference in the structure and form of organisms, which can occur within or between species. It can be caused by genetic factors, environmental factors, or a combination of both. Some examples of morphological variation include: Hair colour, hair quantity, extra body parts, and missing body parts in humans.