Switched morphine Rx from ER to IR? What will be different?

Ive not been reliant on my Rx to function day after day- was hit by a texting teenager while the lane was backed up to a still. I didn't have insurance at the time but I was able to find a plan before the whiplash perma fucked me. I have 0 clues why my 30mg XR is being changed to IR. What should I expect? Will it feel stronger or is it a subtle difference? Ty for insight