What's the difference between testicular cancer and cysts?

Cysts vs cancer: Cancer is a growth of cells that once it gets started it won't stop. It is usually solid. A cyst is like a balloon full of water. Lots of people have cysts and they are a normal finding.

Malignancy: Testicular cancers are malignant, hard, usually painless growths of the testis. Have a very high cure rate with treatment if caught early ; may only require removal of testis. Some require chemotherapy, radiation ;/or abdominal lyph node resection. Will kill if untreated. Cysts are benign, usually of epididymis (spermatocele), rarely of testis itself ; only require removal if symptomatic.