Urethral calculi and kidney stones are not the same concept. Urethral calculi refer to stones located in the urethra, while kidney stones are stones located within the kidney. The cause of urethral calculi is usually due to stones from the kidney or ureter becoming lodged in the urethra, which clinically often results in symptoms such as frequent urination, urgent urination, and difficulty urinating. Severe cases may lead to urinary retention. If kidney stones are small and smooth, they may not cause any symptoms. However, larger kidney stones can cause localized back pain, and if infected, may also lead to high fever. The treatment methods for kidney stones and urethral calculi are also different. Urethral calculi can generally be removed through surgery or endoscopic methods, while the treatment for kidney stones depends on the size and location of the stones.