The renal pelvis and renal calculi are not the same. The renal pelvis is a normal part of the body. Renal calculi are kidney stones and are not normal.
renal calculi
Staghorn calculi
I'm not sure what you mean by "more medical". Renal means having to do with the kidneys, and calculus is Latin for "pebble". Renal calculi are, therefore, "kidney stones" ... but I don't see how that's "more medical."
The renal pelvis is in the kidney.
Renal calculi are formed when the urine becomes supersaturated (overloaded) with mineral compounds that can form stones
Renal pelvis!
ureter
Nephrologist
Renal Calculi are typically called kidney stones. If urine becomes excessively concentrated, some of its solutes begin to crystalize.
Renal Pelvis
The cavity within the kidney that collects urine is called the renal pelvis. From the renal pelvis, urine travels down the ureter to the bladder for storage and eventual excretion.
renal pyramids