Thyroid nodules are more serious than cysts because they are almost always benign and do not have the potential to become malignant, and because cysts are mainly a change in cystic fluid, which is liquid in nature. A thyroid nodule is actually a substantial enlargement of the thyroid gland, which has a higher possibility of malignancy. If a thyroid nodule is graded at grade 4 or higher, it represents the possibility of cancer and needs to be surgically removed in a timely manner, and attention needs to be paid to whether there is metastasis. In summary, cysts are safe, while thyroid nodules are relatively serious.