UTI simply refers to Urinary Tract Infections, while pyelonephritis refers to an infection of the renal pelvis. The urinary tract infections occur more frequently than the pyelonephritis in the body. However, these two kinds of infections occur in the female genders than the male genders. About 50 percent of females have contracted a urinary tract infection at one point or the other in their lives.
They usually contract these during post-menopause, sexual activity, and pregnancy. These infections usually occur with prostate cancer or enlarged prostate in men. The symptoms of UTI include fever, frequent urge, and an increase in urination, pain, or burning while micturating.
On the other hand, the symptoms of pyelonephritis are not really related to the urinary system but include high fever, vomiting, shivering, and nausea. Specifically, UTI happens to be an infection of cystitis (i.e., the urinary bladder), while pyelonephritis is related to an infection of the kidney.