Gull or Tern

Pain Management day. Did relaxation techniques which he swore was not hypnotherapy!  Whatever it is it works. Came home via Links Pond - only gulls to be seen. I'm not sure whether the little bird I captured is a young gull or a young common tern.  Adult terns have black heads so this may be a young one - too dainty to be gull!  Maybe someone can help me out here. The bill (orange with a black tip) would identify it as a tern.