1. The main difference between yellow preserved eggs and black preserved eggs lies in the manufacturing process. Most of the preserved eggs are black or dark brown, and a few are yellow or light red, which are high-quality eggs. If most of them are yellow-brown transparent body, they are immature preserved eggs. 2. There are two kinds of preserved eggs: one is yellow preserved eggs; One is black preserved eggs. The color of preserved eggs is related to its ingredients. The difference between yellow preserved eggs and black preserved eggs lies in the different proportions of yellow lead powder, tea, quicklime, soda ash, salt, charcoal ash and pine and cypress branches. 3, yellow preserved eggs are mostly made of eggs, egg white and yolk ingredients are less, and the storage time is short, which is called "changed eggs". 4. Black preserved eggs are mostly made of duck eggs. Egg whites and egg yolks have heavy ingredients and have been kept for a long time. Pine and cypress branches are added to the ingredients, which is called "preserved eggs". There is nothing wrong with both kinds of preserved eggs, so you can safely eat them.