The main difference between bone density and bone age is the purpose of the examination and the age of the examination. 1. Purpose of examination: Bone density is mainly used to detect the quality of bone, the presence of osteoporosis, and is an important indicator for predicting the risk of fracture. If there is any abnormality in the results, the cause needs to be clarified. Bone age is used to measure bone development and whether it is consistent with age, to determine whether bone development is normal or not, and to roughly determine whether it is possible to continue to grow taller. 2. Bone age: Bone density is mainly used for middle-aged and elderly patients with osteoporosis-related problems, and bone density tests are usually done when osteoporosis is suspected to have occurred. Bone age is usually checked for children under the age of 15, and the purpose of the check is to determine whether they have growth potential. Patients who want to have a bone density and bone age test are advised to go to a regular hospital, consult with a professional doctor, and cooperate with the doctor to complete the relevant tests to avoid blind treatment.