one symbol can have many many meanings...... awareness ribbons being a prime example...
Purple Ribbon :
Meaning: This color is a symbol of pancreatic cancer, testicular cancer, thyroid cancer, domestic violence, ADD, alzheimer's, religious tolerance, animal abuse, the victims of 9/11 including the police and firefighters, Crohn's disease and colitis, cystic fibrosis, lupus, leimyosarcoma, and fibromyalgia
Yellow Ribbon :
Meaning: We've all seen this symbol used to support our troops, but it is also a symbol for MIA/POW, suicide prevention, adoptive parents, amber alerts, bladder cancer, spina bifida, endometriosis, and a general symbol for hope. A yellow ribbon with a heart is used to represent the survivors left behind after a suicide
you can find others here....
Awareness Ribbons Meanings and Colors