Final answer:
The traits an organism displays are known as its phenotype, which is the visible expression of its genotype. The genotype represents the combination of alleles that an organism possesses, which can include traits that are not externally visible.
Step-by-step explanation:
The observable traits expressed by an organism, such as hair color, skin color, height, and build, are described as its phenotype. This differs from the organism's genotype, which is the underlying genetic makeup, consisting of both physically visible and non-expressed alleles for a given gene. For example, in Mendelian genetics, a homozygous dominant (TT) or heterozygous (Tt) pea plant could both have the same green pod phenotype, though their genotypes are different. A recessive trait will only be observed in the phenotype if the organism is homozygous recessive (tt) for that trait.