What is the difference between an epididymal cyst and Spermatocele?

An epididymal cyst is a cyst-like mass (growth) in the epididymis that contains clear fluid.
The epididymis is a long coiled tube that lies above and behind each testicle.
The epididymis collects and transports sperm from the testis to the vas deferens (tubes that transport sperm to the urethra). Spermatoceles are similar to epididymal cysts, but a spermatocele contains fluid and sperm cells. Both are benign growths, meaning they are not cancerous, and they do not interfere with reproduction.
Typically, epididymal cysts and spermatoceles do not cause symptoms and one cannot tell the difference between them by physical exam or even by ultrasound. When discovered, the epididymal cyst is usually about the size of a pea and feels separate from the top of the testis. Spermatoceles typically arise from the head of the epididymis and are felt on the top portion of the testicle.