What is the difference between severe low-back spasms and pain from kidney stones/issues in terms of pain characteristics?

Kidney stone pain: Often radiates to the groin in front on the same side as the stone. Low back pain from strain or nerve root irritation if anything will radiate down the back of the leg on the affected side.

Pain from a kidney: Stone will be present independent of any one position or activity while symptoms related to a spine problem typically are worse with certain positions and better in others.