They both are relatively easy to see since they grow on the front surface of the eye. The cause of each is also similar. Pterygia and pinguecula are frequently found in patients who are exposed to frequent sun, wind, or dust. Usually patients whose occupation or recreation requires them to be outdoors are more prone.
Gender is also a determining factor.
Males develop pterygia or pinguecula approximately three times more often than females. Although pterygia and pinguecula share these similarities their appearance is quite different. A pterygium is a growth on the transparent outer layer of the eye, the conjunctiva. A pinguecula is actually degenerated tissue, and usually appears as a yellowish-brown mass. However, a pterygium may progress and grow onto the cornea posing a visual threat.