Spider veins are smaller red and bluish veins located just beneath the skin surface. Spider veins are usually associated with higher venous pressure in the reticular venous system. They can be associated with hormonal changes, pregnancy, heredity, and reflux in the deeper venous system.
Varicose veins are dilated veins near the surface of the skin that occur secondary to weakened valves and veins in your legs. In veins, there are one-way valves that keep blood flowing from your legs back up to your heart. When the valves are not functioning properly, blood collects in the veins in your legs and the pressure builds up. The veins become weakened, enlarged, and have a twisted appearance and may be dark blue in color. Varicose veins tend to run in families. Other causes of varicose veins include prior pregnancy, standing for long periods of time, age, tall stature, obesity, sedentary lifestyle, and oral contraceptive use. Varicose veins are commonly found in the lower extremities.