They are both very good oils.
Pennzoil Ultra is branded as the race-tested oil line of Pennzoil, specifically designed for cars like SRT Hellcat (0W-40 grade) and other performance cars (other viscosity grades) that are occasionally raced. It has a boosted additive package in comparison to Pennzoil Platinum. The base oil for Platinum flavors is all GTL, so there is no quality variation with flavors there, but there may be viscosity variations.
Pennzoil Euro 0W-40 is full-SAPS, which is for older European cars with less strict emission requirements.
This said, you don't need to drain. The main concern with the full-SAPS (A3/B4) Euro flavor is the the higher phosphorus content, which will accelerate the poisoning of your catalytic converter.
It looks like the SP version of the Euro has a lot of boron now, which is good. I couldn't find a VOA for the SP version of Ultra.
The closest alternative for PP Ultra 0W-40 is Mobil 1 Supercar 0W-40 (dexosR), formerly M1 ESP 0W-40 (dexos2). It is for Corvettes. You using PP Euro instead of PP Ultra in your SRT Hellcat is like someone using M1 FS 0W-40 instead of M1 ESP/Supercar 0W-40 in their Corvette.
https://www.mobil.com/en-us/passenger-vehicle-lube/pds/na-xx-mobil-1-supercar-0w-40
https://www.pennzoil.com/en_us/products/full-synthetic-motor-oils/pennzoil-ultra-platinum.html
https://www.epc.shell.com/documentRetrieve.asp?documentId=114524653
https://bobistheoilguy.com/forums/threads/pennzoil-platinum-euro-0w-40-voa.348615/
https://patents.google.com/patent/CA2967957A1/en