Whole egg, egg yolk, and egg white carry 3 different molecular constitutions. Egg white is high in protein and egg yolk is high in fat. When we mix fat and protein together it creates a different molecular constitution as opposed to when eaten separately. For example, when we make the cake we need separate ingredients to mix together to bind them into a whole, which undergoes a certain process and produces a cake. In the same respect when you mix separate constitutions together it produces a different result. Whilst egg yolks and egg whites come from the same "source" they make up two separate constitutions, which then when put together mix into the digestive system and produce a "different result" / "different reaction." In some cases where there are gut biome imbalances, yeast overgrowths, vitamin deficiencies, and/or digestive enzyme depletion levels, this can also bear an influence the way certain food groups are digested.