I have both and kidney pain is far worse, the stone blocks the tube draining the kidney into your bladder causing the kidney to swell, its like nothing else i have ever encountered, way worse than two forced reps...
Kidney stone pain is like being stabbed relentlessly with an ice pick in your side for however long it takes for the stone to pass- which could be many days. Only a shot of Dilaudid (hydromorphone) made the pain stop. Side note: that's the first drug I was ever given that made me realize why people become addicted to opioids. It was like I was floating in an alternate universe for 5-6 hours, lol.
As you and I have talked before, kidney stones are hell. I got sepsis from the kidney stone surgery (Lithotripsy) because bacteria was introduced during the procedure. I thought the surgeon was joking when he said I had 24 hours to live had I not gotten on the right antibiotics in time. Holy shit. Kidney stones are serious business.