![[image loading]](https://i.redd.it/aou02v00ssqf1.jpeg)
So if you take X damage going through full diameter (3) of storm on live, you would also take X damage going through full diameter (4.5) on PTR.
You would take X/2 damage if you started a unit from the center and moved out on both live and PTR.
Now imagine if unit started at 0.75 distance from the center and moved out. You would take X/4 damage on live and X/3 damage on PTR.
Finally if a unit started at 1.5 distance from center and moved out, it would take 0 damage on live and >0 dmg on PTR.
This isn't even taking into account the fact that storm lasts way longer, so stationary units will always take more dmg.
TLDR: Storm will always deal the same or more damage on PTR (barring some niche scenarios like teleporting with blink/bc) on top of larger surface area + longer duration.