Thyroid cysts and thyroid nodules are different. Generally, thyroid nodules are classified into solid nodules, mixed nodules, and cystic nodules. Most thyroid cysts refer to cystic nodules of the thyroid, meaning that the nodules primarily contain fluid components. Usually, these thyroid cysts are nonfunctional. That is, they contain some fluid, which could be exudate or bloody fluid, but these fluids generally do not cause hormonal level changes. Nodules, on the other hand, often involve functional changes; they can be nodules that produce thyroid hormones or could be cancerous nodules. Therefore, in these respects, thyroid cysts and nodules are different.