More than 2 types. There can be problem with thyroid function were it is either overactive or underactive. The thyroid can be enlarged and cause symptoms like trouble swallowing or breathing due to compression or thyroid function can be normal but pt may have nodule in the thyroid which can sometimes be cancerous and different medicines can affect the size or function of the thyroid.
Hyper vs hypo. Hyperthyroidism happens when your thyroid gland is over active. Hypothyroidism is when the gland is under active. Hyperthyroidism can result in increased metabolism, excessive sweating & rapid heart rate. Hypothyroidism can result in slowed metabolism, feeling cold & dry skin. This list is no where near conclusive. Consult your doctor if you feel that you have thyroid disease and get checked out.