The differences between milk teeth and permanent teeth include eruption time, number, morphology and so on. 1. Eruption time: Milk teeth usually erupt at the age of half to two and a half years, while permanent teeth erupt at the age of six to twelve years. 2. Number: There are normally 20 milk teeth and 28 to 32 permanent teeth, of which 0 to 4 are milk teeth (varies from person to person). 3. Morphology: The milky white color of the milk teeth is smaller than that of the permanent teeth of the same name, and the crowns are short and wide. The necks of the milk teeth are narrowed, the cervical ridges are prominent, the roots of the teeth are obviously narrowed, and the crowns and roots are distinct. The size of the molar teeth increased sequentially, and the mandibular second molar was large at the proximal mesiobuccal cusp, distal mesiobuccal cusp, and distal mesiobuccal cusp. The molar teeth have a large maxillofacial aggregation, a narrowed maxillofacial surface, and indistinct cusps, crests, fossae, and grooves. The specific difference between milk teeth and permanent teeth is recommended to consult a professional doctor.