These two wildflowers have petals which are quite different, yet they are genetically the same. The differences are phenotypic only.

The genotypes can be known to be the same, because different genotypes which are similar cannot persist in the same area. One genotype will always prevail over the other. There can never be exceptions, because evolution always promotes the fittest. Fittest means one or the other, not both.

When differences are great enough to create different species, then they can persist in the same area. There has to be different ecological niches to occupy, before two species can coexist alongside each other.

The differences between these two wildflowers can be known to be phenotypic, which means molecular control, not environmental, because physiology does not allow environments to control significant differences. The whole purpose of millions of years of evolution is to conquer the environment. If environments could significantly alter the characteristics of a species, there would be no protection against adverse environmental effects.

The differences observed here are not trivial. One wildflower has petals which are close to pure white. The other has petals which are dark red. Such color differences are highly important to wildflowers, which is exactly why different phenotypes are needed. The different flower colors will show up more or less easily in contrast with the background, and different insects are attracted to different colors.

It is also common to see differences in morphology (shape) with the differences in color of wildflower petals. In this case, the white petals are larger than the red petals.
 
Such differences in color and shape are pretty much standard with wildflowers. But phenotypic differences are greatly reduced in domesticated species, because human selection gradually diminishes the tendency of species to produce phenotypic variations. For this reason, garden flowers will show less phenotypic variation than wildflowers. Variations are also reduced by highly stable environments, as many of the domesticated flowers came from.

Spurge Phenotypes