Nephrology :

Nephrology is the field of medicine that focuses on diagnosing and treating diseases that affect the kidneys. Like urologists, nephrologists receive extensive education and training in their field. Unlike urology, the scope of nephrology does not include other parts of the urologic system. Nephrologists don't deal with disorders of the male reproductive system either. The focus of nephrology is on the kidneys. A nephrologist may also deal with factors linked to kidney disorders, such as high blood pressure or heart disease. However, they would not treat these problems outside of their relationship to the kidneys.

Urology :

Urologists, the doctors who practice urology, have received extensive education and training in the urinary system. Urology is considered a surgical specialty, but urologists do much more than perform surgical procedures. Many urologists are in general practice and can treat a variety of urologic conditions. Other urologists have a specialty in a certain area, like urologic cancer, male infertility, or pediatric urology.