Not an expert I havent owned either in a couple years but they look like pacu to me. In person they are easier to tell because sd are like chrome color. They will heal fine from what looks like heater burn on the side just keep the water clean and maybe add a bit of salt and keep an eye out for infections
The person said they were SD, they are very silver/ chrome. I thought pacu were a little darker, but the red makes me think pacu. Either way the person also said they are at max size ,which they aren't if they are pacu lol
It's hard to tell but look closely their lips/mouth are puffed up and white. I added salt to tank. Guessing all the fins and tail will heal up quickly too.