Variation in gene frequencies is referred to as genetic variation.
Individual differences or population differences can both be referred to as genetic variation.
Genetic variation is primarily caused by mutation, but other factors such as sexual reproduction and genetic drift also play a role.
The traits showing variations are observed under polygenic inheritance in which a trait is governed by more than two genes.
For example: If skin colour of human beings is considered, there is a vast variety of skin shades present among us. The genes for each colour are having different genetic codes but still giving out the same trait, i.e. skin colour.
In this sense, human height, colour of human eyes, can be considered as human traits that show variations.
Final Answer: The two human traits that show variation are skin color and height of human.