Phenotype 1 is dominant to over phenotype 2 (coded by the same Gene, or set of genes), if a hybrid having an allele for each, expresses phenotype 1. Phenotype 2 is then called recessive. See video. This is called total dominance, or full penetrance.

Wiki (it talks about it being a property of gealleles, but it's a property of phenotypes!, see here)

Pleiotropic genes. May have both dominant and recessive traits, see video. Sickle cell anemia is caused by a particular mutation in the gene of the $\beta$ globin protein of hemoglobin. That mutation gives rise to sickle cell anemia, which is a recessive trait, but it gives rise to sickle cells, which is a dominant trait. See here

These properties as well as the Locus (Genetics), give rise to different modes of inheritance.

PHENOTYPE AND GENOTYPE

A full understanding of genetic dominance requires looking at the Genotype-phenotype map, which often requires Systems biology approaches.

Codominance

Partial dominance

Or incomplete penetrance. See video

Incomplete dominance

Pseudodominance

Molecular basis of dominance

If you are Heterozygote, and one of the alleles gives rise to an Enzyme that doesn't work, that may give rise to a recessive or a dominant trait.

If the enzymes don't interact, the ineffective enzyme won't change the phenotype (unless that enzyme is the rate limiting effect, and then the pathway will go more slowly). This is essentially a recessive trait. See video

If the ineffective enzymes interact with and negatively affect the other enzymes, it virtually stop the pathway, resulting in a Dominant negative trait.